We are in the thought process of removing night storage heaters and
having new full central heating and hot water from a kerosene fired
boiler.

The issue is whether we go for a combi boiler or a system boiler with a
much smaller HW cylinder than at present and with the smaller cylinder
relocated to the loft.

The boiler will be an outside boiler.

The length of hot water to taps/shower pipe runs from a combi boiler will
be great and need a lot of running off before the hot water comes through
but it avoids the need for a cylinder.

A system boiler would give a heated water store that would be almost
directly above bathrooms and kitchen but would be in the loft (single
storey dwelling) so supplies to taps would run down walls rather than up
from underfloor.

I'm more tempted by a system with cylinder as I have also read some
reviews that say that kerosene combi are not as good at producing HW as a
gas fired.

Any thoughts please on system vs combi and also efficiency of kerosene
combi for the supply of HW.

Thanks

Bev submitted this idea :
I'm more tempted by a system with cylinder as I have also read some
reviews that say that kerosene combi are not as good at producing HW as a
gas fired.

I had a cylinder for stored water installed back in mid-80's (gas
boiler) and have resisted suggestions to replace it with a combi twice
since then. Combi boilers are just about OK for houses which are not
much occupied, but they have great disadvantages for most people..

1. They waste water until it heats up.
2. Increased wear on the boiler, which has to fire everytime HW is
needed.
3. They are more inefficient heating water.

Stored systems are more complicated and costly to install, plus take up
extra space. Unused HW looses heat from the cylinder.

Heating engineers like replacing stored with combi systems because they
get the value of the scrap copper.

Harry Bloomfield, Esq. wrote:
Bev submitted this idea :
I'm more tempted by a system with cylinder as I have also read some
reviews that say that kerosene combi are not as good at producing HW as a
gas fired.

I had a cylinder for stored water installed back in mid-80's (gas
boiler) and have resisted suggestions to replace it with a combi twice
since then. Combi boilers are just about OK for houses which are not
much occupied, but they have great disadvantages for most people..

1. They waste water until it heats up.
2. Increased wear on the boiler, which has to fire everytime HW is
needed.
3. They are more inefficient heating water.

Stored systems are more complicated and costly to install, plus take up
extra space. Unused HW looses heat from the cylinder.

Heating engineers like replacing stored with combi systems because they
get the value of the scrap copper.


We stayed with a relative for a few days this week who has a combi, it was
noticeable that if we were having a shower and someone turned on a hot tap
in the kitchen, you got a €˜cold surprise. Conversely, we have two showers
which are pump assisted and we can run both at the same time and you dont
notice if someone turns on a hot tap. We have a hot water storage tank.

True, the hot tank €˜sits there and is losing heat but, in practice, it is
so well insulated it seems to get heated up and require very little energy
to maintain it. It isnt unknown for me to turn it off when going away for
a day, come back, remember to turn the heating on but not the water heater,
and not notice until residual hot water from before the short trip has been
used- perhaps a day.

On Sat, 01 Feb 2020 11:53:45 GMT, Harry Bloomfield, Esq.
wrote:

Bev submitted this idea :
I'm more tempted by a system with cylinder as I have also read some
reviews that say that kerosene combi are not as good at producing HW as a
gas fired.

I had a cylinder for stored water installed back in mid-80's (gas
boiler) and have resisted suggestions to replace it with a combi twice
since then. Combi boilers are just about OK for houses which are not
much occupied, but they have great disadvantages for most people..

1. They waste water until it heats up.
2. Increased wear on the boiler, which has to fire everytime HW is
needed.
3. They are more inefficient heating water.


We experience this to an extreme with our combi as the kitchen is
quite a way from the boiler, though thankfully the shower is near the
boiler.

What would suit us is a small tank above the kitchen warmed by the CH
system and maybe a thermostatically controlled element. At a previous
property a similar arrangement worked well from an open coal fired CH
system. Do such systems exist?




--
AnthonyL

Why do scientists need to BELIEVE in anything?

On Sat, 01 Feb 2020 05:13:35 -0600, Bev wrote:

The length of hot water to taps/shower pipe runs from a combi
boiler will be great and need a lot of running off before the hot
water comes through but it avoids the need for a cylinder.

Not just at first start either - if you are using hot water in short
bursts you get a slug of cold water followed by excessively hot each
time you turn off and on again; ok if you're running a bath,
wasteful otherwise. Avoid combi if you can.

On 01/02/2020 12:34, AnthonyL wrote:
On Sat, 01 Feb 2020 11:53:45 GMT, Harry Bloomfield, Esq.
wrote:

Bev submitted this idea :
I'm more tempted by a system with cylinder as I have also read some
reviews that say that kerosene combi are not as good at producing HW as a
gas fired.

I had a cylinder for stored water installed back in mid-80's (gas
boiler) and have resisted suggestions to replace it with a combi twice
since then. Combi boilers are just about OK for houses which are not
much occupied, but they have great disadvantages for most people..

1. They waste water until it heats up.
2. Increased wear on the boiler, which has to fire everytime HW is
needed.
3. They are more inefficient heating water.


We experience this to an extreme with our combi as the kitchen is
quite a way from the boiler, though thankfully the shower is near the
boiler.

What would suit us is a small tank above the kitchen warmed by the CH
system and maybe a thermostatically controlled element. At a previous
property a similar arrangement worked well from an open coal fired CH
system. Do such systems exist?

There is nothing to stop you running a combi with a conventional Y plan
system as well. So stored HW for baths etc, then on demand mains
pressure potable water for kitchen / showers etc.


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On 01/02/2020 11:13, Bev wrote:

We are in the thought process of removing night storage heaters and
having new full central heating and hot water from a kerosene fired
boiler.

The issue is whether we go for a combi boiler or a system boiler with a
much smaller HW cylinder than at present and with the smaller cylinder
relocated to the loft.

Why a smaller cylinder?

The boiler will be an outside boiler.

The length of hot water to taps/shower pipe runs from a combi boiler will
be great and need a lot of running off before the hot water comes through
but it avoids the need for a cylinder.

A system boiler would give a heated water store that would be almost
directly above bathrooms and kitchen but would be in the loft (single
storey dwelling) so supplies to taps would run down walls rather than up
from underfloor.

I'm more tempted by a system with cylinder as I have also read some
reviews that say that kerosene combi are not as good at producing HW as a
gas fired.

Any thoughts please on system vs combi and also efficiency of kerosene
combi for the supply of HW.

HW production with a combi really just comes down to the maximum
instantaneous power. Smaller boilers (e.g. 24kW) will do a nice shower
but will be slower filling a bath. A more powerful one (say 35kW) will
do better all round and can cope with two showers at once (assuming the
cold mains supply is up to it).

Have you considered a system boiler and an unvented cylinder? That gives
the advantages of both at once - lots of stored hot water and mains
pressure delivery, with no need for an additional header tank.

Guidance on choosing a system he

http://wiki.diyfaq.org.uk/index.php/..._Water_Systems

Unvented systems he

http://wiki.diyfaq.org.uk/index.php/Unvented_DHW


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

In article ,
John Rumm wrote:
There is nothing to stop you running a combi with a conventional Y plan
system as well. So stored HW for baths etc, then on demand mains
pressure potable water for kitchen / showers etc.

IMM is alive and well. ;-) Why would you heat up and keep hot a cylinder
just for baths?

--
*Income tax service - We‘ve got what it takes to take what you've got.

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

In message , John
Rumm writes
On 01/02/2020 12:34, AnthonyL wrote:
On Sat, 01 Feb 2020 11:53:45 GMT, Harry Bloomfield, Esq.
wrote:

Bev submitted this idea :
I'm more tempted by a system with cylinder as I have also read some
reviews that say that kerosene combi are not as good at producing HW as a
gas fired.

I had a cylinder for stored water installed back in mid-80's (gas
boiler) and have resisted suggestions to replace it with a combi twice
since then. Combi boilers are just about OK for houses which are not
much occupied, but they have great disadvantages for most people..

1. They waste water until it heats up.
2. Increased wear on the boiler, which has to fire everytime HW is
needed.
3. They are more inefficient heating water.

We experience this to an extreme with our combi as the kitchen is
quite a way from the boiler, though thankfully the shower is near the
boiler.
What would suit us is a small tank above the kitchen warmed by the
CH
system and maybe a thermostatically controlled element. At a previous
property a similar arrangement worked well from an open coal fired CH
system. Do such systems exist?

There is nothing to stop you running a combi with a conventional Y plan
system as well. So stored HW for baths etc, then on demand mains
pressure potable water for kitchen / showers etc.

Also consider a thermal store. Avoids the issues of a combi but retains
flow rates through small bore piping.

--
Tim Lamb

On Sat, 01 Feb 2020 14:53:55 +0000, John Rumm wrote:

On 01/02/2020 11:13, Bev wrote:

We are in the thought process of removing night storage heaters and
having new full central heating and hot water from a kerosene fired
boiler.

The issue is whether we go for a combi boiler or a system boiler with a
much smaller HW cylinder than at present and with the smaller cylinder
relocated to the loft.

Why a smaller cylinder?

Because the one that is in the cylinder cupboard is 263l and is a low
pressure system fed from loft header tank and it takes up far too much
space. My thoughts were to go with a pressurised unvented cylinder
(which, I think, is what you describe below---) in the loft with the
relief being discharged outside into the drain. The discharge route is
easily achievable.



Have you considered a system boiler and an unvented cylinder? That gives
the advantages of both at once - lots of stored hot water and mains
pressure delivery, with no need for an additional header tank.

Guidance on choosing a system he

http://wiki.diyfaq.org.uk/index.php/..._Water_Systems

Unvented systems he

http://wiki.diyfaq.org.uk/index.php/Unvented_DHW

Thanks for the links (and to others for their responses too)

On 01/02/2020 14:59, Dave Plowman (News) wrote:
In article ,
John Rumm wrote:
There is nothing to stop you running a combi with a conventional Y plan
system as well. So stored HW for baths etc, then on demand mains
pressure potable water for kitchen / showers etc.

IMM is alive and well. ;-) Why would you heat up and keep hot a cylinder
just for baths?



One of the complaints about combi boilers is about how long it takes to
fill a bath.

That gives a combi boiler user an extra 4 minutes to have a wank before
having a bath.



--
Adam

AnthonyL wrote :
What would suit us is a small tank above the kitchen warmed by the CH
system and maybe a thermostatically controlled element. At a previous
property a similar arrangement worked well from an open coal fired CH
system. Do such systems exist?

I understand you can buy an electrically heated local system (to where
it is consumed), which stores the combi heated water keeping it hot.
Thus you get hot water quickly, without the usual delay of a combi.

Bev wrote:
On Sat, 01 Feb 2020 14:53:55 +0000, John Rumm wrote:

On 01/02/2020 11:13, Bev wrote:

We are in the thought process of removing night storage heaters and
having new full central heating and hot water from a kerosene fired
boiler.

The issue is whether we go for a combi boiler or a system boiler with a
much smaller HW cylinder than at present and with the smaller cylinder
relocated to the loft.

Why a smaller cylinder?

Because the one that is in the cylinder cupboard is 263l and is a low
pressure system fed from loft header tank and it takes up far too much
space. My thoughts were to go with a pressurised unvented cylinder
(which, I think, is what you describe below---) in the loft with the
relief being discharged outside into the drain. The discharge route is
easily achievable.



Have you considered a system boiler and an unvented cylinder? That gives
the advantages of both at once - lots of stored hot water and mains
pressure delivery, with no need for an additional header tank.

Guidance on choosing a system he

http://wiki.diyfaq.org.uk/index.php/..._Water_Systems

Unvented systems he

http://wiki.diyfaq.org.uk/index.php/Unvented_DHW

Thanks for the links (and to others for their responses too)


You can get horizontal unvented cylinders if lack of headroom is limiting
your choice of cylinder capacity. No idea how they compare price wise but
I would expect them to be more expensive just because demand is lower.
Still, it might give you more options.

Eg.
https://www.kingspan.com/gb/en-gb/pr...rect-cylinders

Tim

--
Please don't feed the trolls

On Sat, 01 Feb 2020 17:21:23 +0000, Tim+ wrote:

You can get horizontal unvented cylinders if lack of headroom is
limiting your choice of cylinder capacity. No idea how they compare
price wise but I would expect them to be more expensive just because
demand is lower.
Still, it might give you more options.

Eg.
https://www.kingspan.com/gb/en-gb/pr...ders/unvented-
hot-water-cylinders/ultrasteel-horizontal-indirect-cylinders

Tim

Thanks but headroom is not a problem.

In message , Bev
writes
On Sat, 01 Feb 2020 17:21:23 +0000, Tim+ wrote:

You can get horizontal unvented cylinders if lack of headroom is
limiting your choice of cylinder capacity. No idea how they compare
price wise but I would expect them to be more expensive just because
demand is lower.
Still, it might give you more options.

Eg.
https://www.kingspan.com/gb/en-gb/pr...ders/unvented-
hot-water-cylinders/ultrasteel-horizontal-indirect-cylinders

Tim

Thanks but headroom is not a problem.

You will miss the waste heat in your now spacious airing cupboard:-)

--
Tim Lamb

On 01/02/2020 11:13, Bev wrote:
I'm more tempted by a system with cylinder as I have also read some
reviews that say that kerosene combi are not as good at producing HW as a
gas fired.
The one thing I have noticed is that oil boilers have never failed to
provide decent hot water.

I'd put a mains pressure tank in the loft - then you have all the
advantages of the combi - mains pressure hot water, no shower pumnps -
and all the advantages of a system boiler with a tank - high flow rate
of hot water.

If your water is hard, put in a water softener to protect it.

--
"The great thing about Glasgow is that if there's a nuclear attack it'll
look exactly the same afterwards."

Billy Connolly

One oft overlooked point is that domestic natural gas supplies to domestic houses is typically 66kW maximum unless you have a commercial supply instead, a bit like the electricity board's 100A 1 phase supply or 3 X 100A 3 phase supply.

Why is this important? Well my house has a 38kW vaillant combi. So that leaves me a 28kW supply margin for my two gas ovens and 6 ring hob.

It is possible to build combis with higher rated flat plate domestic hot water heat exchangers and burners. However you run the risk that trying to consume gas at a faster flow rate than the gas meter and governed can supply, the internal gas pipework pressure will drop below 22 mBar.

Supply Vs demand issues for LPG or oil tanks may not be a factor as presumably they can be designed to be able to supply what the peak demand of the house is going to be, i.e. the boiler going at full pelt if rated higher than a domestic gas boiler and with the cooker going too in the case of LPG.

I am sure an OFTEC or LPG accredited engineer can offer more comment.

So to the original op, you may find that a decently sized combi on a decently sized LPG/Oil tank may not have the same issue as encountered by natural gas combis.

On Sat, 01 Feb 2020 20:41:16 +0000, Tim Lamb wrote:

In message , Bev
writes
On Sat, 01 Feb 2020 17:21:23 +0000, Tim+ wrote:

You can get horizontal unvented cylinders if lack of headroom is
limiting your choice of cylinder capacity. No idea how they compare
price wise but I would expect them to be more expensive just because
demand is lower.
Still, it might give you more options.

Eg.
https://www.kingspan.com/gb/en-gb/pr...ter-cylinders/
unvented-
hot-water-cylinders/ultrasteel-horizontal-indirect-cylinders

Tim

Thanks but headroom is not a problem.

You will miss the waste heat in your now spacious airing cupboard:-)

I think the boss is looking to put a heater in it (just joking)

On Sun, 02 Feb 2020 03:52:48 +0000, The Natural Philosopher wrote:

On 01/02/2020 11:13, Bev wrote:
I'm more tempted by a system with cylinder as I have also read some
reviews that say that kerosene combi are not as good at producing HW as
a gas fired.
The one thing I have noticed is that oil boilers have never failed to
provide decent hot water.

Thanks

I'd put a mains pressure tank in the loft - then you have all the
advantages of the combi - mains pressure hot water, no shower pumnps -
and all the advantages of a system boiler with a tank - high flow rate
of hot water.

Again thanks

If your water is hard, put in a water softener to protect it.

Fortunately we have a soft water supply

In article ,
NY wrote:
At our old house, we had a Grant combi oil boiler, mains-pressure fed.
And you could run the hot tap into the bath at full flow (same flow
rate as cold tape, since it was mains-fed) and the water was red hot.
So it definitely did not take a long time to fill a bath.

It's normal with a stored system to use 22mm pipes and taps to the bath.
Giving a far higher flow rate than 15mm. The important thing for filling a
bath quickly. Unlike say a shower where you might prefer high pressure
jets of water. Dunno of any combi which can match the flow rate of a 22mm
system, properly designed.

--
*Ham and Eggs: Just a day's work for a chicken, but a lifetime commitment

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

Let me quell the myth that oil combis are not as good as gas combis. Most of them are better. Look at the Firebird range and outdoor models of their boilers are available. However you might like to consider a heat pump which subject to meeting various conditions can attract Renewable Heat Initiative (RHI) payments. Bear in mind heat pumps produce lower temperature hot water to circulate through the radiators so require greater surface areas of emitters. Both oil or heat pump sources can work with an unvented hot water cylinder. If you go to a heat pump once a week or so the temperature of the hot water cylinder needs boosting with a standard immersion heater to avoid risk of legionella.
If the old airing cupboard is cold it's easy to add a small radiator to compensate for the loss of the heat from the old cylinder.