good morning

i have just gutted a four bedroom townhouse over threes floors - ground / first and attic.

i have therefore to decide what heating / hot system i should put back in as there is nothing right now - not even a copper pipe!! there is mains gas and electric.

it is of 1950's construction, so the walls are not very well insulated - the roof is well insulated. i am thinking of a radiator system as i am on a limited budget and underfloor heating will be too expensive.

water wise - there are three showers (1 on each floor and it is likely that at least two will require water at the same time. there is also a bath on the first floor but unlikely to be used much.

there's plenty of space to mount pretty much any system but i really don't know what's best - probably most concern is the demand for hot water - a simple combi boiler could not handle it. and i only want one electric shower as an absolute emergency.

i should say that i don't expect to live in the property for more than 5 years at the most so i do not want to pay huge amounts for a renewable energy system that takes years and years to re-coup the investment.

any advice gratefully received. thanks

In message ,
writes

there's plenty of space to mount pretty much any system but i really
don't know what's best - probably most concern is the demand for hot
water - a simple combi boiler could not handle it. and i only want one
electric shower as an absolute emergency.

Doubtless you will receive plenty of conflicting advice, but, given that
you have gas, I would go for a traditional gas boiler and showers fed
via a large hot water cylinder with immersion heater for emergencies.
Other will advise on calculation of boiler and tank sizes - take the
advice and add 10 per cent.

Our system is oil fired but otherwise as above. Plenty of capacity for
the traditional radiator central heating, plus hot water. The water is
heated twice a day, for one hour early morning, and another hour mid
afternoon. Two of us shower in the morning, and one in the evening.
Very occasional baths. We never run out of hot water.

Two caveats. One, I'm biased and hate combis, and Two, although we have
several showers in the house, for no particular reason, we rarely seem
to run more than one simultaneously.

--
Graeme

On 08/03/2016 07:49, wrote:
good morning

i have just gutted a four bedroom townhouse over threes floors - ground / first and attic.

i have therefore to decide what heating / hot system i should put back in as there is nothing right now - not even a copper pipe!! there is mains gas and electric.

it is of 1950's construction, so the walls are not very well insulated - the roof is well insulated. i am thinking of a radiator system as i am on a limited budget and underfloor heating will be too expensive.

water wise - there are three showers (1 on each floor and it is likely that at least two will require water at the same time. there is also a bath on the first floor but unlikely to be used much.

there's plenty of space to mount pretty much any system but i really don't know what's best - probably most concern is the demand for hot water - a simple combi boiler could not handle it. and i only want one electric shower as an absolute emergency.

i should say that i don't expect to live in the property for more than 5 years at the most so i do not want to pay huge amounts for a renewable energy system that takes years and years to re-coup the investment.

any advice gratefully received. thanks


Some thoughts:

If you have a conventional system with a hot water tank, then you can
have an immersion heater for use if the boiler fails or you want to stop
it for any reason.

OTOH If you have cold water tanks in the roof you need to ensure that
the water does not freeze in the winter, especially if the house is left
unoccupied.

Another issue is whether you have a system boiler. These are more
complex, presumably cost more and are more tedious to fill. OTOH you
have to install a header tank for a conventional system.

My fully pumped conventional system uses fully motorised valves which
don't move if the programmer switches the heating off and on to achieve
proportional control.

I am not a fan of thermostatic radiator valves. I would regard a wired
in programmable thermostat as essential, preferably with remote control.

Many programmable thermostats are single channel. OK for the CH but I
like to have the HW off when it is not required.









--
Michael Chare

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On 08/03/16 07:49, wrote:
good morning

i have just gutted a four bedroom townhouse over threes floors -
ground / first and attic.

i have therefore to decide what heating / hot system i should put
back in as there is nothing right now - not even a copper pipe!!
there is mains gas and electric.

it is of 1950's construction, so the walls are not very well
insulated - the roof is well insulated. i am thinking of a radiator
system as i am on a limited budget and underfloor heating will be too
expensive.

water wise - there are three showers (1 on each floor and it is
likely that at least two will require water at the same time. there
is also a bath on the first floor but unlikely to be used much.

there's plenty of space to mount pretty much any system but i really
don't know what's best - probably most concern is the demand for hot
water - a simple combi boiler could not handle it. and i only want
one electric shower as an absolute emergency.

i should say that i don't expect to live in the property for more
than 5 years at the most so i do not want to pay huge amounts for a
renewable energy system that takes years and years to re-coup the
investment.

any advice gratefully received. thanks


First thing: do you have a cavity and is it insulated - if not, do that
first.

Then big efficient radiators. Bigger than you think, subject to space.

Use the manufacturer tables to ascertain power output and then double
the size over what it needs to maintain steady state (or what you think
it needs).

For little extra cost (ordinary rads are not expensive), it will:

1) Keep the boiler happy avoiding cycling;

2) Give you a faster warm up from cold so less unnecessary heating;

3) Allow the heating to run at a lower water temperature which is more
efficient on the boiler (upto a point) and more comfortable to humans
(usually - opinions vary).

For example - a house I have with 2" cavity wall blown fibre (old) and
3" celotex in the roof requires a total of about 3-4kW electric heaters
to maintain steady state 21C downstairs when outside is 5C ish.

However, it takes a day to 2 days to come up from stone cold with 4kW.

So I will be aiming to put in a total about 5 times that at least in
terms of max output power of radiators at the usual delta-T, then I can
drop the water temperature (and thus the delta-T) a bit too.

On the basis of what you've said if you have not got figures for how
lossy your house it, then I would aim for 3-4kW for a massive room (ie
really large lounge), 3-4kW for a large bedroom, 2-3kW for a medium
bedroom and 1-2kW for a tiny bedroom and so on.

And zone it, at least by floor.

You'll save more in rapid warm up when needed, then being able to turn
it off in unused areas when not than any amount of fancy wibbling with
heat pumps, solar panels and the like will ever give you.


On the subject of insulation, if you have no cavity, do you have the
space to put 1-2" celotex on the inside walls (at least external walls)
then plasterboard? Even 1" over bare brick will make a very large
difference to both comfort and heat loss.


Cheers,

Tim

On 08/03/2016 07:49, wrote:
good morning

i have just gutted a four bedroom townhouse over threes floors - ground / first and attic.

i have therefore to decide what heating / hot system i should put back in as there is nothing right now - not even a copper pipe!! there is mains gas and electric.

it is of 1950's construction, so the walls are not very well insulated - the roof is well insulated. i am thinking of a radiator system as i am on a limited budget and underfloor heating will be too expensive.

water wise - there are three showers (1 on each floor and it is likely that at least two will require water at the same time. there is also a bath on the first floor but unlikely to be used much.

there's plenty of space to mount pretty much any system but i really don't know what's best - probably most concern is the demand for hot water - a simple combi boiler could not handle it. and i only want one electric shower as an absolute emergency.

i should say that i don't expect to live in the property for more than 5 years at the most so i do not want to pay huge amounts for a renewable energy system that takes years and years to re-coup the investment.

any advice gratefully received. thanks

I would use a conventional boiler - not a combi - to heat both the
radiators and a hot water cylinder. Install a *large* cylinder and
insulate it well.

Zone the heating system - probably one zone per floor - making four
zones in all including the hot water. [Depending on how the rooms are
used, some different zoning scheme may be appropriate - living areas,
sleeping areas, etc. regardless of floor.]

The primary system should be non-vented.

The DHW system could be vented - with with a large header tank in the
attic, or you could use a non-vented mains pressure cylinder. Only use
the latter if you if you've got *really* good mains pressure and flow -
otherwise bath filling - and particularly showers - will be limited by
what the mains can supply. I would tend to favour a vented (gravity)
system with large diameter pipes from the cylinder to the principal
usage points, and with booster pumps for the showers. [You'll need to
feed cold water from the header tank to the showers as well as hot from
the cylinder].

With a 3 storey house, you will inevitably have long pipe runs from the
cylinder to some of the taps - possibly making some sort of constant
circulation system worth considering so as to avoid having to waste a
lot of water before any hot gets to the taps. Alternatively, for
relatively low usage applications such as kitchen sinks, you might
consider an electrically heated device (Quooker, etc.) which stores a
few litres of boiling water in an insulated container under the sink and
supplies virtually instant hot water to the taps.
--
Cheers,
Roger
____________
Please reply to Newsgroup. Whilst email address is valid, it is seldom
checked.

On Tuesday, 8 March 2016 08:29:59 UTC, News wrote:
Doubtless you will receive plenty of conflicting advice, but, given that
you have gas, I would go for a traditional gas boiler and showers fed
via a large hot water cylinder with immersion heater for emergencies.

Yes.

However, as combis are often cheaper than corresponding non-combi versions, you could use the combi hot water for one shower, or the kitchen tap, which will give you instant hot water in that location without waiting for the cylinder to heat.

If you're only going to be in the house for 5 years then you might consider whether the additional cost of an unvented hot water cylinder is really necessary. Put the electric shower in the attic, and you may find you have enough head from an attic tank to give adequate showers on the ground and first floors without needing pumps - they'll be low pressure but you can get good flow.

For zoning, consider putting the bathroom towel rails on one zone so you can have them on in summer for drying towels without heating the rest of the house.

Owain

On 08/03/2016 07:49, wrote:
good morning

i have just gutted a four bedroom townhouse over threes floors -
ground / first and attic.

i have therefore to decide what heating / hot system i should put
back in as there is nothing right now - not even a copper pipe!!
there is mains gas and electric.

it is of 1950's construction, so the walls are not very well
insulated - the roof is well insulated. i am thinking of a radiator
system as i am on a limited budget and underfloor heating will be too
expensive.

The consensus is a system boiler and I agree with this. Combis are great
for small houses.

Oversize the radiators. The cooler the CH return temperature the more
efficient the boiler can be.

One issue is that with a conventional CH/HW system with a diverter is
the boiler outlet temperature is fixed, leading to a conflict on
temperature required to heat HW and the lower temperature desired for
CH. A heat store type arrangement might be more appropriate.

water wise - there are three showers (1 on each floor and it is
likely that at least two will require water at the same time. there
is also a bath on the first floor but unlikely to be used much.

This is more of an issue. I would suggest at least one is electric. For
two or more there is the issue of only having 100A incoming fuses. I
understand there is no allowable diversity on two "water heaters", 50%
allowed on further "water heating".

On Tuesday, 8 March 2016 08:49:08 UTC+1, wrote:
good morning

I have just gutted a four bedroom townhouse over threes floors

I have therefore to decide what heating / hot system I should put back
in as there is nothing right now - not even a copper pipe!!

It is of 1950's construction, so the walls are not very well insulated.

At this point, I would insulate the walls. If you have a cavity, get it
filled. If not, consider whether you want to add external insulation or
internal.

External:
+ The walls act as a heat store, keeping it cool in summer and warm in
winter.
+ No loss of space inside
+ No problem with interstitial condensation (because the thickness of
the wall stays warm.
- May look naff outside, and particularly difficult if you are in a
conservation area.
- Difficulty detailing at roof and windows.

Internal:
+ Wall is outside the insulation, so house heats up quickly when you
come in in the evening.
+ External appearance unaltered
- Need to be careful about interstitial condensation. Need a really
*complete* vapour barrier.
- Some loss of internal space.

When we insulated the inside of our bathroom with 100mm wood fibre
(Pavadentro) it went from the coldest room in the house to the warmest.

- the roof is well insulated.
Really? 200mm of glass fibre?

I am thinking of a radiator system as I am on a limited budget
Sensible enough.

water wise - there are three showers (1 on each floor and it is likely ?
that at least two will require water at the same time.

Sounds like you need a system boiler and a hot water tank or thermal store.

Think about siting the tank and plumbing so that you can fit solar thermal
later, even if you don't fit it now.

I should say that I don't expect to live in the property for more than
5 years at the most so I do not want to pay huge amounts for a renewable
energy system that takes years and years to re-coup the investment.

A nice warm house that you can gloat about how little it costs to heat will
sell much more readily when it comes time to sell. (You may not make the
pound costs back, but the reduction in stress when it sells quickly has
value - and you may make the money back too.)

On 08/03/16 12:39, Fredxxx wrote:

The consensus is a system boiler and I agree with this. Combis are great
for small houses.

No, they are crap even for small houses.

If they are big enough to deliver hot water for a shower, or have a heat
bank, they are more expensive than a system boiler and a pressurised hot
water tank.

A combi and a heat bank is like a windmill and a battery. Tow bad ideas
bolted together to make a truly awful and expensive solution.




--
The theory of Communism may be summed up in one sentence: Abolish all
private property.

Karl Marx

On Tuesday, 8 March 2016 14:11:41 UTC+1, The Natural Philosopher wrote:
On 08/03/16 12:39, Fredxxx wrote:

The consensus is a system boiler and I agree with this. Combis are great
for small houses.

No, they are crap even for small houses.

Rubbish. The combi in our three-bedroom house was fine. Two or three
adults. It struggled if two people wanted a shower at the same time, but
some people don't view that as the end of the world (others do of course).

On Tue, 8 Mar 2016 08:29:48 +0000, News
wrote:

In message ,
writes

there's plenty of space to mount pretty much any system but i really
don't know what's best - probably most concern is the demand for hot
water - a simple combi boiler could not handle it. and i only want one
electric shower as an absolute emergency.

Doubtless you will receive plenty of conflicting advice, but, given that
you have gas, I would go for a traditional gas boiler and showers fed
via a large hot water cylinder with immersion heater for emergencies.
Other will advise on calculation of boiler and tank sizes - take the
advice and add 10 per cent.

Our system is oil fired but otherwise as above. Plenty of capacity for
the traditional radiator central heating, plus hot water. The water is
heated twice a day, for one hour early morning, and another hour mid
afternoon. Two of us shower in the morning, and one in the evening.
Very occasional baths. We never run out of hot water.

Two caveats. One, I'm biased and hate combis, and Two, although we have
several showers in the house, for no particular reason, we rarely seem
to run more than one simultaneously.

You just told us why.
"Two of us shower in the morning".

--

Graham.

%Profound_observation%

On 08/03/2016 14:35, Martin Bonner wrote:
On Tuesday, 8 March 2016 14:11:41 UTC+1, The Natural Philosopher wrote:
On 08/03/16 12:39, Fredxxx wrote:

The consensus is a system boiler and I agree with this. Combis are great
for small houses.

No, they are crap even for small houses.

Rubbish. The combi in our three-bedroom house was fine. Two or three
adults. It struggled if two people wanted a shower at the same time, but
some people don't view that as the end of the world (others do of course).

Agreed, though I might put the limit down to 2 bedrooms.

For a small house it can save a lot of room where tanks would be.

It's ideal for someone at work all day, where no water is stored so no
heat loss; where the proximity of kitchen and bathroom often mean little
water need be run until you get hot water.

No 22mm pipes taking to flush with hot water at low pressure before you
get hot water out of a kitchen hot tap. Power shower without any further
equipment, just a simple thermostatic mixing bar.

Some people are blinkered, and in denial, of the advantages.

In message , Graham.
writes
On Tue, 8 Mar 2016 08:29:48 +0000, News
wrote:

Two caveats. One, I'm biased and hate combis, and Two, although we have
several showers in the house, for no particular reason, we rarely seem
to run more than one simultaneously.

You just told us why.
"Two of us shower in the morning".

But the two who shower in the morning may, or may not do so
simultaneously.
--
Graeme

On 08/03/2016 09:49, Michael Chare wrote:
On 08/03/2016 07:49, wrote:
good morning

i have just gutted a four bedroom townhouse over threes floors -
ground / first and attic.

i have therefore to decide what heating / hot system i should put back
in as there is nothing right now - not even a copper pipe!! there is
mains gas and electric.

it is of 1950's construction, so the walls are not very well insulated
- the roof is well insulated. i am thinking of a radiator system as i
am on a limited budget and underfloor heating will be too expensive.

water wise - there are three showers (1 on each floor and it is likely
that at least two will require water at the same time. there is also
a bath on the first floor but unlikely to be used much.

there's plenty of space to mount pretty much any system but i really
don't know what's best - probably most concern is the demand for hot
water - a simple combi boiler could not handle it. and i only want one
electric shower as an absolute emergency.

i should say that i don't expect to live in the property for more than
5 years at the most so i do not want to pay huge amounts for a
renewable energy system that takes years and years to re-coup the
investment.

any advice gratefully received. thanks


Some thoughts:

If you have a conventional system with a hot water tank, then you can
have an immersion heater for use if the boiler fails or you want to stop
it for any reason.

OTOH If you have cold water tanks in the roof you need to ensure that
the water does not freeze in the winter, especially if the house is left
unoccupied.

Another issue is whether you have a system boiler. These are more
complex, presumably cost more and are more tedious to fill. OTOH you
have to install a header tank for a conventional system.

My fully pumped conventional system uses fully motorised valves which
don't move if the programmer switches the heating off and on to achieve
proportional control.

I am not a fan of thermostatic radiator valves. I would regard a wired
in programmable thermostat as essential, preferably with remote control.

Many programmable thermostats are single channel. OK for the CH but I
like to have the HW off when it is not required.

Other points I would add:

a) Use radiators with a rounded top rather than a welded seam.

b) Install a heated towel rail in the bathroom.

c) Install drain points in the pipework to each radiator that won't
drain without one.

d) If you have a hot water tank, get one with 50mm insulation on it.


--
Michael Chare

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On 08/03/16 19:37, Michael Chare wrote:

Other points I would add:

a) Use radiators with a rounded top rather than a welded seam.

Rust?


b) Install a heated towel rail in the bathroom.

Mine heat towels better than heating the room. Probably just me.

c) Install drain points in the pipework to each radiator that won't
drain without one.

d) If you have a hot water tank, get one with 50mm insulation on it.


A new boiler will cost £4,500 + gas costs.

For mere amusement, over 5 years could it be cheaper on electric with
ceiling fitted infra-red panels, room occupancy sensors and much better
room insulation fitted?

--
Adrian C

On 08/03/2016 19:48, Adrian Caspersz wrote:
On 08/03/16 19:37, Michael Chare wrote:

Other points I would add:

a) Use radiators with a rounded top rather than a welded seam.

Rust?


b) Install a heated towel rail in the bathroom.

Mine heat towels better than heating the room. Probably just me.

c) Install drain points in the pipework to each radiator that won't
drain without one.

d) If you have a hot water tank, get one with 50mm insulation on it.


A new boiler will cost £4,500 + gas costs.

For mere amusement, over 5 years could it be cheaper on electric with
ceiling fitted infra-red panels, room occupancy sensors and much better
room insulation fitted?


Why do you think rust would be a problem for round top radiators?

I presume your £4,500 is really the cost for all the CH parts!


--
Michael Chare

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On 08/03/16 22:10, Michael Chare wrote:
On 08/03/2016 19:48, Adrian Caspersz wrote:
On 08/03/16 19:37, Michael Chare wrote:

Other points I would add:

a) Use radiators with a rounded top rather than a welded seam.

Rust?


Why do you think rust would be a problem for round top radiators?


What was your justification for the rounded top. Just interested, that's
all. Guessing some issue with leaks or rust for a seam?

I presume your £4,500 is really the cost for all the CH parts!


£1000 boiler cost,
£2000 4 to 5 days of labour,
£1500 other bits - all inc VAT.

--
Adrian C

On 08/03/2016 22:30, Adrian Caspersz wrote:
On 08/03/16 22:10, Michael Chare wrote:
On 08/03/2016 19:48, Adrian Caspersz wrote:
On 08/03/16 19:37, Michael Chare wrote:

Other points I would add:

a) Use radiators with a rounded top rather than a welded seam.

Rust?


Why do you think rust would be a problem for round top radiators?


What was your justification for the rounded top. Just interested, that's
all. Guessing some issue with leaks or rust for a seam?


I just think they are nicer than those with welded seams at the top.


I presume your £4,500 is really the cost for all the CH parts!


£1000 boiler cost,
£2000 4 to 5 days of labour,
£1500 other bits - all inc VAT.


Labour! This is UK.d-i-y


--
Michael Chare

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On Tuesday, 8 March 2016 19:37:30 UTC, Michael Chare wrote:
On 08/03/2016 09:49, Michael Chare wrote:
On 08/03/2016 07:49, wrote:

i have therefore to decide what heating / hot system i should put back
in as there is nothing right now - not even a copper pipe!! there is
mains gas and electric.

it is of 1950's construction, so the walls are not very well insulated
- the roof is well insulated. i am thinking of a radiator system as i
am on a limited budget and underfloor heating will be too expensive.

on a limited budget you could check out the boilers on ebay. Should save you most of a grand.

water wise - there are three showers (1 on each floor and it is likely
that at least two will require water at the same time.

gas boiler & cylinder then. Again there are used cylinders around at times.

water - a simple combi boiler could not handle it. and i only want one
electric shower as an absolute emergency.

cheaper to add an immersion element

i should say that i don't expect to live in the property for more than
5 years at the most so i do not want to pay huge amounts for a

Another issue is whether you have a system boiler.

costlier to fix

I am not a fan of thermostatic radiator valves. I would regard a wired
in programmable thermostat as essential, preferably with remote control.

TRVs are only semi thermostatic, not truly thermostatic. But it beats no thermostat on each rad. A separate real thermostat per room is certainly better, but if you'll be moving out I'm not sure the expense is warranted.

Many programmable thermostats are single channel.

Bimetal stats are fine. Technology doesn't always produce a win.

b) Install a heated towel rail in the bathroom.

pointless gimmicks imho. OTOH a future buyer might like it.

d) If you have a hot water tank, get one with 50mm insulation on it.

or place it where you can stick more than 2" of loft insulation round it.


NT

On 08/03/2016 09:56, Tim Watts wrote:

First thing: do you have a cavity and is it insulated - if not, do that
first.

Then big efficient radiators. Bigger than you think, subject to space.

I've found in both the victorian flat over our shop and our 1960/70
detached house with non insulated floors, when using the "radiator
sizing charts" they've always been wildly over sized. When I sized up
the radiators for the bedrooms at home to work with UFH flow temp. I
needed massive rads. So in the end based on previous experiences I
simply took the biggest single panel finned radiator that would fit in
the space where space wasn't a variable i.e. under windows (single so it
didn't stick right out into the room) and used radiators that "looked"
the right size in the hall and master bedroom.

All chuck out more than enough heat even with flow never exceeding 55
degrees MAX. to bring bedroom up to temp quickly.

Not a very scientific approach but one based on previous results of a
"by the rule book" sizing.

1) Keep the boiler happy avoiding cycling;

Wouldn't an over-sized radiator system make the boiler cycle more than a
system where the radiators are perfectly sized for all but the rare week
or 2 every 10 years or more when temperatures go into minus double-digits?

Easier to add an additional heat source in those rare and exceptional
conditions than to design a system with huge over-capacity that will
rarely be required.


2) Give you a faster warm up from cold so less unnecessary heating;

It's all energy consumed. Bring it up to temp really quick with a high
input or slower with a lower input. A steadier and more constant lower
heat input would be preferable from a comfort perspective.
Weather compensated Boiler keeps temp nice all the time. With UFH it
means the floor is always just right. If I push 55 degrees around all
the time, the floor goes off and cools rapidly (between joists so no
thermal mass) which means a floor that's cold long before the room stat
has dropped to it's low set-point to fire up the zone and re-heat the floor.


3) Allow the heating to run at a lower water temperature which is more
efficient on the boiler (upto a point) and more comfortable to humans
(usually - opinions vary).

Definitely. And weather compensation is an absolute must-have for both
economy and comfort.


For example - a house I have with 2" cavity wall blown fibre (old) and
3" celotex in the roof requires a total of about 3-4kW electric heaters
to maintain steady state 21C downstairs when outside is 5C ish.

However, it takes a day to 2 days to come up from stone cold with 4kW.

So I will be aiming to put in a total about 5 times that at least in
terms of max output power of radiators at the usual delta-T, then I can
drop the water temperature (and thus the delta-T) a bit too.

When would you ever need to heat from stone-cold? I'd always leave the
heating set to perhaps 15 degrees if I could be arsed to re-program all
the room stats which I wouldn't.

On 08/03/2016 07:49, wrote:

any advice gratefully received. thanks

What I did was....
Get a decent combi based not on heat out-put but water flow capacity.
i.e. big enough to drive 2 showers at once. This gave me a boiler with
more than enough capacity to meet current (time of install) and future
(the new extension that wasn't on the cards at the time) demands.

IIRC my boiler is 36Kw which is plenty man-enough to give 2 good showers
simultaneously. Fitting something like "Mira Eco" shower heads to both
showers come in at a miserly 7 litres/minute draw per shower with the
"feel" of a much larger flow due to aeration of the water.

Weather compensation on the boiler is a must-have in my mind and if you
can run your system at UFH temp and still maintain comfort levels you're
onto a winner BUT if you find you have to run significantly hotter
you've got that big-boiler backup and you'll still modulate down to UFH
temperatures during spring and autumn anyway.

Planning a system based on the most extreme conditions expected is
completely wrong to me. If you're charging someone to do their heating
then yes it makes sense as you'd not want people saying their house is
too cold even if it is just a week every 10 years but doing your own
system then I'd base it on a much leaner figure that covers 95% of the
heating requirement from an economy and more importantly an aesthetical
point of view. Who wants to buy a house with the biggest radiators in
the world dominating every room? Screams of expensive house to heat
with very ugly rooms to the future buyer.

IMO of course IANAPP

On Wednesday, 9 March 2016 16:52:49 UTC, www.GymRatZ.co.uk wrote:

When would you ever need to heat from stone-cold? I'd always leave the
heating set to perhaps 15 degrees if I could be arsed to re-program all
the room stats which I wouldn't.


People can overworry about that. It really doesn't matter if it takes a day to heat up fully.


NT

On 09/03/16 16:52, www.GymRatZ.co.uk wrote:
On 08/03/2016 09:56, Tim Watts wrote:

First thing: do you have a cavity and is it insulated - if not, do that
first.

Then big efficient radiators. Bigger than you think, subject to space.

I've found in both the victorian flat over our shop and our 1960/70
detached house with non insulated floors, when using the "radiator
sizing charts" they've always been wildly over sized. When I sized up
the radiators for the bedrooms at home to work with UFH flow temp. I
needed massive rads. So in the end based on previous experiences I
simply took the biggest single panel finned radiator that would fit in
the space where space wasn't a variable i.e. under windows (single so it
didn't stick right out into the room) and used radiators that "looked"
the right size in the hall and master bedroom.

All chuck out more than enough heat even with flow never exceeding 55
degrees MAX. to bring bedroom up to temp quickly.

Not a very scientific approach but one based on previous results of a
"by the rule book" sizing.

1) Keep the boiler happy avoiding cycling;

Wouldn't an over-sized radiator system make the boiler cycle more than a
system where the radiators are perfectly sized for all but the rare week
or 2 every 10 years or more when temperatures go into minus double-digits?

I wouldn't have thought so - in that the boiler will at least not be
cycling on the water stat, only the room stat(s) - and the latter will
have quite a big hysteresis.

Easier to add an additional heat source in those rare and exceptional
conditions than to design a system with huge over-capacity that will
rarely be required.

Aye - it's a matter of space/cost trade off. If you have a long external
wall, IMHO it's worth putting a long thin (single panel) rad along it
even if it's oversized.

But I was not suggesting putting in massive rads to the point where it
consumes excessive floor space or the costs go through the roof.


2) Give you a faster warm up from cold so less unnecessary heating;

It's all energy consumed. Bring it up to temp really quick with a high
input or slower with a lower input. A steadier and more constant lower
heat input would be preferable from a comfort perspective.
Weather compensated Boiler keeps temp nice all the time. With UFH it
means the floor is always just right. If I push 55 degrees around all
the time, the floor goes off and cools rapidly (between joists so no
thermal mass) which means a floor that's cold long before the room stat
has dropped to it's low set-point to fire up the zone and re-heat the floor.


3) Allow the heating to run at a lower water temperature which is more
efficient on the boiler (upto a point) and more comfortable to humans
(usually - opinions vary).

Definitely. And weather compensation is an absolute must-have for both
economy and comfort.


For example - a house I have with 2" cavity wall blown fibre (old) and
3" celotex in the roof requires a total of about 3-4kW electric heaters
to maintain steady state 21C downstairs when outside is 5C ish.

However, it takes a day to 2 days to come up from stone cold with 4kW.

So I will be aiming to put in a total about 5 times that at least in
terms of max output power of radiators at the usual delta-T, then I can
drop the water temperature (and thus the delta-T) a bit too.

When would you ever need to heat from stone-cold? I'd always leave the
heating set to perhaps 15 degrees if I could be arsed to re-program all
the room stats which I wouldn't.


Coming back from holidays - or if you work away a lot.

On 09/03/2016 17:47, Tim Watts wrote:

Wouldn't an over-sized radiator system make the boiler cycle more than a
system where the radiators are perfectly sized for all but the rare week
or 2 every 10 years or more when temperatures go into minus
double-digits?

I wouldn't have thought so - in that the boiler will at least not be
cycling on the water stat, only the room stat(s) - and the latter will
have quite a big hysteresis.

Don't all boilers modulate both pump and burner these days?

My old boiler uses "V.C.O." (variable controlled output)
I'd have thought it was commonplace these days as it's got to be closing
in on 10 years old now.

Nominal Output To Heating 50/30C 30.7kW
Minimum Output To Heating 50/30C 5.1kW

80/60 F/R changes to anything between 28.4kW and 4.5kW

Hot water is variable between 4.8-36.0kW

On 09/03/16 18:56, www.GymRatZ.co.uk wrote:
On 09/03/2016 17:47, Tim Watts wrote:

Wouldn't an over-sized radiator system make the boiler cycle more than a
system where the radiators are perfectly sized for all but the rare week
or 2 every 10 years or more when temperatures go into minus
double-digits?

I wouldn't have thought so - in that the boiler will at least not be
cycling on the water stat, only the room stat(s) - and the latter will
have quite a big hysteresis.

Don't all boilers modulate both pump and burner these days?


Within limits, yes. I only really know about Viessmann and WB as those
were the two I was reading teh spec sheets on.

My old boiler uses "V.C.O." (variable controlled output)
I'd have thought it was commonplace these days as it's got to be closing
in on 10 years old now.

Nominal Output To Heating 50/30C 30.7kW
Minimum Output To Heating 50/30C 5.1kW

80/60 F/R changes to anything between 28.4kW and 4.5kW


That is really low - but that will still require some well sized rads if
only a couple of them are demanding heat.

Hot water is variable between 4.8-36.0kW

Nice top limit

On 09/03/2016 20:14, Tim Watts wrote:

Hot water is variable between 4.8-36.0kW

Nice top limit


That's how I manage 2 showers at the same time.

On 09/03/16 19:15, Chris Hogg wrote:

You say about a boiler "Use the manufacturer tables to ascertain power
output and then double the size over what it needs to maintain steady
state (or what you think it needs)", and you also give ball-park
suggestions for the wattages needed to heat some rooms, e.g. 3-4kW for
a large bedroom. Do those figures include the doubling factor,

yes - that's includes padding. I *can* maintain a bedroom on 1kW on a
moderately cold day (if the other heaters are keeping other rooms warm)
but 1kW from stone cold needs to be run flat out for a day to get the
room even remotely warm from a standing start.

2kW (heater max setting - I don't like leaving them on remote control on
this setting, hence the 1kW earlier) gets the job done faster, but it's
still hours.

Actually, I just dug out my spreadsheet based on the biggest rads I can
get in without compromising space or aesthetics and these are my working
figures at delta-T=50C (the usual dT to calculate at):

Main bedroom = 2.4kW
Daughter's bedroom = 2.8kW
Son's = 2.1kW
Kitchen/diner (2 external walls, large) = 3.8kW
Hall = 1.7kW (long, 2 external doors)
Lobby (2nd side "hall" with stairs, lots of cold here) = 2.7kW
Upstairs dormer (large open single space over whole floor) = 5.6kW

Conservatory UFH = 2kW (will maintain steady state at outside temp =
about 5C)
Conservatory Myson wet air fan = 4.6kW (this is worthwhile - fast heatup
when needed for short periods in winter)

Shower room UFH (off "lobby") = 300W

Bathroom (off main hall) towel rail - 700W




I'd like more in the main bedroom so will play with some different rad
types. However, I think I could reduce the upstairs a LOT - 3kW would be
enough as I've observed a lot of heat rises from the ground floor and
the solar gain is pretty good up there.

The kitchen really needs 3.8kW to get it going from cold.

The bathroom needs nothing much if the hall is heated (fully islanded).
The shower room is under powered - might need a small rad there too.

The conservatory will be run to just keep the floor tepid in winter and
the air blower used to fast heat when needed (not that much obviously).
In spring/autumn, the UFH should manage quite well for much higher
occupancy as it's will be our day room then. Winter, we'll be sensible
and not use it much, but UFH ticking over will help keep things dry.


The idea above is that the sheer power is available on cold days and
returning from breaks to get the place nice FAST, also in mornings (we
like to sleep nice and cold). But most of the time I reckon we could
turn the water temperature right down to a delta-T of 40C or less (or
rather the weather comp could).




That's a total load of about 30kW.

or
should I double up the sum I get for the bungalow, which is
approximately 18kW on the basis of your numbers as they stand? I must
say, doubling that to 36kW seems a bit excessive for a small bungalow.

On 09/03/16 20:24, www.GymRatZ.co.uk wrote:
On 09/03/2016 20:14, Tim Watts wrote:

Hot water is variable between 4.8-36.0kW

Nice top limit


That's how I manage 2 showers at the same time.




That's what I'd like. I have my central distribution pipework in 22mm,
with separate drops in 15mm to the kitchen, bathroom, shower room (when
done) and outside. That's a happy coincidence of having the under stair
cupboard (actually a big walk in cupboard) dead centre and between the
boiler site and everything else.

I am also including flow limiting valves (BES, they take an insertable
cartridge available in 8 or so flow rates) to balance the system - so
running a bath will not starve everything else - and so that a tap on
full in a small basin does not a) blow back in your face; b) defeat the
basin overflow. Rather nifty little valves that include a full bore
isolator too.

On 3/8/2016 8:29 AM, News wrote:
In message ,
writes

there's plenty of space to mount pretty much any system but i really
don't know what's best - probably most concern is the demand for hot
water - a simple combi boiler could not handle it. and i only want one
electric shower as an absolute emergency.

Doubtless you will receive plenty of conflicting advice, but, given that
you have gas, I would go for a traditional gas boiler and showers fed
via a large hot water cylinder with immersion heater for emergencies.
Other will advise on calculation of boiler and tank sizes - take the
advice and add 10 per cent.

Our system is oil fired but otherwise as above. Plenty of capacity for
the traditional radiator central heating, plus hot water. The water is
heated twice a day, for one hour early morning, and another hour mid
afternoon. Two of us shower in the morning, and one in the evening.
Very occasional baths. We never run out of hot water.

Two caveats. One, I'm biased and hate combis, and Two, although we have
several showers in the house, for no particular reason, we rarely seem
to run more than one simultaneously.


+1 (although I am on gas and only have one shower).

If you are not going for a mains pressure cylinder (more expensive, more
to go wrong) you will benefit from a double impeller shower pump for the
top floor. Don't economise, get a Stuart Turner. I suspect that a single
3 bar pump might be sufficient for all three showers. Certainly I
normally throttle the flow on my 2 bar one. Might be worth plumbing the
shower feeds in 22 mm?

On Wednesday, 9 March 2016 21:29:00 UTC, newshound wrote:

top floor. Don't economise, get a Stuart Turner. I suspect that a single
3 bar pump might be sufficient for all three showers. Certainly I
normally throttle the flow on my 2 bar one. Might be worth plumbing the
shower feeds in 22 mm?

He has 3 floors, he doesn't need a pump


NT

On 09/03/16 20:55, Chris Hogg wrote:
On Wed, 9 Mar 2016 20:30:15 +0000, Tim Watts
wrote:

On 09/03/16 19:15, Chris Hogg wrote:

You say about a boiler "Use the manufacturer tables to ascertain power
output and then double the size over what it needs to maintain steady
state (or what you think it needs)", and you also give ball-park
suggestions for the wattages needed to heat some rooms, e.g. 3-4kW for
a large bedroom. Do those figures include the doubling factor,

yes - that's includes padding.

Thanks. So a 20kW boiler will be just fine.


Plus hot water

I'd say 20kW will be too weedy.

On 3/9/2016 10:11 PM, wrote:
On Wednesday, 9 March 2016 21:29:00 UTC, newshound wrote:

top floor. Don't economise, get a Stuart Turner. I suspect that a single
3 bar pump might be sufficient for all three showers. Certainly I
normally throttle the flow on my 2 bar one. Might be worth plumbing the
shower feeds in 22 mm?

He has 3 floors, he doesn't need a pump


NT

Might do on the top floor, especially if not much of a loft. And if you
pump one, you might get better flow when more than one is in use by
pumping them all.

On 3/8/2016 3:22 PM, Fredxxx wrote:
On 08/03/2016 14:35, Martin Bonner wrote:
On Tuesday, 8 March 2016 14:11:41 UTC+1, The Natural Philosopher wrote:
On 08/03/16 12:39, Fredxxx wrote:

The consensus is a system boiler and I agree with this. Combis are
great
for small houses.

No, they are crap even for small houses.

Rubbish. The combi in our three-bedroom house was fine. Two or three
adults. It struggled if two people wanted a shower at the same time, but
some people don't view that as the end of the world (others do of
course).

Agreed, though I might put the limit down to 2 bedrooms.

For a small house it can save a lot of room where tanks would be.

It's ideal for someone at work all day, where no water is stored so no
heat loss; where the proximity of kitchen and bathroom often mean little
water need be run until you get hot water.

No 22mm pipes taking to flush with hot water at low pressure before you
get hot water out of a kitchen hot tap. Power shower without any further
equipment, just a simple thermostatic mixing bar.

Some people are blinkered, and in denial, of the advantages.

I've always said they are fine, e.g. in a small holiday cottage which I
use sometimes use. But they are *hopeless* in a larger family house.

newshound wrote:

you will benefit from a double impeller shower pump for the
top floor. Don't economise, get a Stuart Turner

I'm sure they're great, but if the O/P wants something with less brass,
for less brass, I've not had a peep of a problem from my Salamander in
nearly 7 years ...

On 09/03/16 22:20, Tim Watts wrote:
On 09/03/16 20:55, Chris Hogg wrote:
On Wed, 9 Mar 2016 20:30:15 +0000, Tim Watts
wrote:

On 09/03/16 19:15, Chris Hogg wrote:

You say about a boiler "Use the manufacturer tables to ascertain power
output and then double the size over what it needs to maintain steady
state (or what you think it needs)", and you also give ball-park
suggestions for the wattages needed to heat some rooms, e.g. 3-4kW for
a large bedroom. Do those figures include the doubling factor,

yes - that's includes padding.

Thanks. So a 20kW boiler will be just fine.


Plus hot water

I'd say 20kW will be too weedy.

I had a 12kw boiler in a 2000 sq ft house.

And all the hot water I could handle.
Mains pressure tank and decent insulation.


--
"What do you think about Gay Marriage?"
"I don't."
"Don't what?"
"Think about Gay Marriage."

On 09/03/2016 20:38, Tim Watts wrote:

That's what I'd like. I have my central distribution pipework in 22mm,
with separate drops in 15mm to the kitchen, bathroom, shower room (when
done) and outside. That's a happy coincidence of having the under stair
cupboard (actually a big walk in cupboard) dead centre and between the
boiler site and everything else.

Sounds very similar to my own layout.
The "airing cupboard" was originally a boiler cupboard converted later
in life to a hot water cylinder cupboard and wall boiler which I ripped
out and it now houses the UFH maifold and acts as a riser from
downstairs to upstairs.

22mm pipes on everything then spurred off in 15mm to kitchen, shower
room etc


I am also including flow limiting valves (BES, they take an insertable
cartridge available in 8 or so flow rates) to balance the system - so
running a bath will not starve everything else - and so that a tap on
full in a small basin does not a) blow back in your face; b) defeat the
basin overflow. Rather nifty little valves that include a full bore
isolator too.

So far I've found that the 22mm - 15mm serves to adequately balance the
system without any problem although we don't currently have a main
bathroom as it was gutted 3 or 4 years ago and is on the "to-do" list.

Also have main 22mm cold water feed running through water softener
before it hits the boiler so cold/hot are all soft.

As part of the current extension project the builders destroyed the old
black water-mains from the street as it ran along the foundation route
so I re-ran the pipe from the street meter in 32mm to the boiler side of
the house rather than the garage which cut down the meter to house
distance by a good 15 to 20m.

Another un-planned upgrade ticked off the list.

In article ,
Martin Bonner wrote:
Rubbish. The combi in our three-bedroom house was fine. Two or three
adults. It struggled if two people wanted a shower at the same time,
but some people don't view that as the end of the world (others do of
course).

My main complaint would be that the reliability isn't as good as a system
boiler. And with a storage system you can have an immersion as a backup
for not much money.

Easy enough to heat a room with a fan heater or whatever if the boiler
fails, but getting enough hot water by boiling kettles etc a real pain.

--
*You never really learn to swear until you learn to drive *

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
Fredxxx wrote:
No 22mm pipes taking to flush with hot water at low pressure before you
get hot water out of a kitchen hot tap. Power shower without any further
equipment, just a simple thermostatic mixing bar.

You don't use 22mm to a kitchen tap from a storage system. Only to a bath
or a high volume shower.

--
*Arkansas State Motto: Don't Ask, Don't Tell, Don't Laugh.

Dave Plowman London SW
To e-mail, change noise into sound.

On 3/10/2016 10:24 AM, Dave Plowman (News) wrote:

My main complaint would be that the reliability isn't as good as a system
boiler. And with a storage system you can have an immersion as a backup
for not much money.

Easy enough to heat a room with a fan heater or whatever if the boiler
fails, but getting enough hot water by boiling kettles etc a real pain.

We have a combi, and our backup is an electric shower. The dishwasher
heats its own water, so not many kettles of water needed in the kitchen.
A few oil-filled radiators and the fireplace in the living room, can
keep the place warm.

In article ,
S Viemeister wrote:
On 3/10/2016 10:24 AM, Dave Plowman (News) wrote:

My main complaint would be that the reliability isn't as good as a system
boiler. And with a storage system you can have an immersion as a backup
for not much money.

Easy enough to heat a room with a fan heater or whatever if the boiler
fails, but getting enough hot water by boiling kettles etc a real pain.

We have a combi, and our backup is an electric shower.

Ah - right. My shower is an ancient Aqualiza low pressure high flow type.
Lovely shower - but not exactly energy efficent. But then the shower
cubical is lit by halogen. ;-)


The dishwasher
heats its own water, so not many kettles of water needed in the kitchen.

I don't possess a dishwasher. Do it all by hand. ;-) But different for a
family.

A few oil-filled radiators and the fireplace in the living room, can
keep the place warm.

Yes - generally not expensive to get electric heaters for an emergency.
Running them, a different matter. I've got fan heaters as they're small to
store.

--
*If horrific means to make horrible, does terrific mean to make terrible?

Dave Plowman London SW
To e-mail, change noise into sound.