Still chewing over with hubby what way to do CH and DWS.

Learnt a lot from all of you boys in the last few weeks - thanks. Reading
with interest the "Thermostatic or electric shower from combi" thread posted
by Eno. Makes a lot more sense when you understand the terms without a
dictionary of gas and plumbing terms!

The latest brainstorm from us is thus:
Replace oil boiler and all tanks with condensing gas combi.
Leave crappy water supply of 15mm as is - (11 litres per minute) and plumb
it to all kitchen equipment - sink, dishwasher etc.
Bring in new 35mm water supply and plumb all "upstairs" stuff with new water
supply through combi (and kitchen hot tap). Will feed 2 loos, 2 showers and
1 bath.
This is after friendly plumber's advice that just upgrading the supply as is
mightn't be enough for our needs as a family of five.
Combi will do CH and one large underfloor heating area and bathroom stuff.

Big story, one small question:
To avoid digging up lovely new tarmac drive, we would like to bring it
through grass to near the front door and then dig across paved step area
which would be relatively simple to re-lay, in under door area and straight
up the hall (needs levelled anyway to tile, its like a dog's hind leg at
mo). But can we? Is it silly to bring 35mm water supply through a hallway
in case of leaks etc? Is it stupid to put a gradual bend in the pipe just
to save a drive?

Like John's idea of the Mira 415 shower valve. Avoids Bart-Homer-esque
moments in the shower, and singed kiddies. Any drawbacks?

Ok that's 4 questions, I'll stop now.

Many thanks
Suzanne ¦^D

Suz wrote:

Replace oil boiler and all tanks with condensing gas combi.

But why? Oil is cheaper and (IMO) nicer to work with. Why do you
want to switch to gas?


To avoid digging up lovely new tarmac drive, we would like to bring it
through grass to near the front door and then dig across paved step area
which would be relatively simple to re-lay, in under door area and straight
up the hall (needs levelled anyway to tile, its like a dog's hind leg at
mo). But can we? Is it silly to bring 35mm water supply through a hallway
in case of leaks etc? Is it stupid to put a gradual bend in the pipe just
to save a drive?

I don't see a problem with that.

--
Grunff

"Grunff" wrote in message
...
Suz wrote:

Replace oil boiler and all tanks with condensing gas combi.

But why? Oil is cheaper and (IMO) nicer to work with. Why do you
want to switch to gas?

We have been advised by a few different un-involved parties that the gas
bills are lower over time.
The oil boiler is getting on a bit and needs something done soon It is
housed in a like brick ediface that is right where the kitchen extension
will go . This will not be needed if we change it's location to
understairs . Getting shot of the hot tank means we can have a separate
bath and shower in the main bathroom We want to do a roof space
conversion and it would be great to get rid of the tanks up there. All
this will be replaced by one boiler in the big understairs cupboard which
just hordes junk at the mo. And the natural gas conduit is already laid
under the new drive The oil boiler had a spill over it a couple of years
ago and it *stinks*. Not nice to work with (sadly shakes head), won't be
sorry to see it go .

More than

Suzanne

"Suz" wrote in message
...

Still chewing over with hubby what way to do CH and DWS.

Learnt a lot from all of you boys in the last few weeks - thanks. Reading
with interest the "Thermostatic or electric shower from combi" thread
posted
by Eno. Makes a lot more sense when you understand the terms without a
dictionary of gas and plumbing terms!

The latest brainstorm from us is thus:
Replace oil boiler and all tanks with condensing gas combi.
Leave crappy water supply of 15mm as is - (11 litres per minute) and plumb
it to all kitchen equipment - sink, dishwasher etc.
Bring in new 35mm water supply and plumb all "upstairs" stuff with new
water
supply through combi (and kitchen hot tap). Will feed 2 loos, 2 showers
and
1 bath.
This is after friendly plumber's advice that just upgrading the supply as
is
mightn't be enough for our needs as a family of five.

35mm will not be enough? See the water company, and see what they will
deliver in flow and pressure.

Combi will do CH and one large underfloor heating area and bathroom stuff.

Big story, one small question:
To avoid digging up lovely new tarmac drive, we would like to bring it
through grass to near the front door and then dig across paved step area
which would be relatively simple to re-lay, in under door area and
straight
up the hall (needs levelled anyway to tile, its like a dog's hind leg at
mo). But can we? Is it silly to bring 35mm water supply through a
hallway
in case of leaks etc? Is it stupid to put a gradual bend in the pipe just
to save a drive?

No it is not. See the water company first. Some only allow the shortest
route from the water mains to the house.

Like John's idea of the Mira 415 shower valve. Avoids Bart-Homer-esque
moments in the shower, and singed kiddies. Any drawbacks?

Ok that's 4 questions, I'll stop now.

Suzanne,

If you are bringing in a new 35mm water main, then why are you leaving the
existing 15mm main? The water company will charge you extra for two mains
entering a property. 35mm will be fine, assuming you will have the pressure
and flow, which most 35mm pipes do. See the water company.

2 showers, one bath, 5 people. I would go for a heat bank and a gas
condensing boiler. See Christian McArdles posting on the current thread Hot
water System. He has bought a new DPS Pandora heat bank and is fitting it
in his loft. The same price as a Megaflow unvented cylinder and no
overflows. This will do all you want in a hot water mains pressure system
and no cold water storage tank. Then fit a condensing boiler. The UFH side
is easy enough. See the Polyplumb or Speedfit web sites.
http://ww.heatweb.com

A combi will do what you want, but it will be a top of the range
state-of-the-art very expensive job. It may work out cheaper though and you
save space.

Yes fit the Mira 415 shower, or the Screwfix job - I posted the details. I
fitted a 415 for a friend 13 years ago. I have used it occasionally and it
operates very well. It reacts very quick to pressure fluctuations in the
system. You notice a pressure change rather than a temperature change.

Another suggestion will be to install a pressure equalising valve at the
main stop cock. One pie directly to a heat bank, or combi, and the other,
to the cold outlets. Then cheaper shower mixers can be used. The
equalisation valve will do all the house, inc the two showers. You will
have to price up two 415s and two shower mixers and a 22mm equalisation
valve. The valves are available from Plumb Center.



---
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"Suz" wrote in message
...

"Grunff" wrote in message
...
Suz wrote:

Replace oil boiler and all tanks with condensing gas combi.

But why? Oil is cheaper and (IMO) nicer to work with. Why do you
want to switch to gas?

We have been advised by a few different un-involved parties that the gas
bills are lower over time.
The oil boiler is getting on a bit and needs something done soon It is
housed in a like brick ediface that is right where the kitchen extension
will go . This will not be needed if we change it's location to
understairs . Getting shot of the hot tank means we can have a separate
bath and shower in the main bathroom We want to do a roof space
conversion and it would be great to get rid of the tanks up there. All
this will be replaced by one boiler in the big understairs cupboard which
just hordes junk at the mo.

Consider fitting two combi's - two can be had for around £1,000. One for
upstairs CH and one for down, with room stat/timer for each. Split the hot
water taps between the two. One does the bath and shower over it, the other
the second shower, etc.

It is easy to pipe up with one doing upstairs and the other down. Also
backup in the house as if one is down then at least there is heat and hot
water in the house. Make sure the gas supply can cope. You have a max of
212 cu foot of gas available. Divide the Btus/hr by 100 to the cu foot per
hour of the appliance. So, 90,000 Btu/hr is 90 cu foot per hour. You cold
have one condensing combi for downstairs (UFH) and cheaper a regular combi
for upstairs. Two regular combi's be cheap to run as most of the time
upstairs should be off. No need to have on during the day, only mornings
and evenings.




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On Tue, 7 Oct 2003 23:06:10 +0100, "Suz" wrote:

Still chewing over with hubby what way to do CH and DWS.

Learnt a lot from all of you boys in the last few weeks - thanks. Reading
with interest the "Thermostatic or electric shower from combi" thread posted
by Eno. Makes a lot more sense when you understand the terms without a
dictionary of gas and plumbing terms!

The latest brainstorm from us is thus:
Replace oil boiler and all tanks with condensing gas combi.
Leave crappy water supply of 15mm as is - (11 litres per minute) and plumb
it to all kitchen equipment - sink, dishwasher etc.
Bring in new 35mm water supply and plumb all "upstairs" stuff with new water
supply through combi (and kitchen hot tap). Will feed 2 loos, 2 showers and
1 bath.
This is after friendly plumber's advice that just upgrading the supply as is
mightn't be enough for our needs as a family of five.
Combi will do CH and one large underfloor heating area and bathroom stuff.


My only concern here is whether even a large combi is going to give
you a fast enough production rate of hot water if you want to use the
showers and bath simultaneously.

Consider that in effect in cold weather the specified flow rate of the
combi will be all that you will get at shower temperature. If the
mains supply is (say) 8 degrees and the shower 40, then at the
standard 35 degree uplift temperature by the boiler you will not be
mixing much cold in with this and the combi flow rate becomes the
total rate.

Check out the flows that you want for the showers (personally I
wouldn't accept less than 15 litres/min each) plus the bath and you
may be in trouble with a combi - even a large one.

You may find that you need to have some form of heat storage, whether
it be a pressurised cylinder or a heatbank. There is nothing to
stop you heating one of these from a combi using its CH side and
motorised valves (effectively like a non-combi), then using the hot
water production from the combi to run some of the hot water services
and the stored water the rest.....




..andy

To email, substitute .nospam with .gl

"Andy Hall" wrote in message
...
On Tue, 7 Oct 2003 23:06:10 +0100, "Suz" wrote:

Still chewing over with hubby what way to do CH and DWS.

Learnt a lot from all of you boys in the last few weeks - thanks.
Reading
with interest the "Thermostatic or electric shower from combi" thread
posted
by Eno. Makes a lot more sense when you understand the terms without a
dictionary of gas and plumbing terms!

The latest brainstorm from us is thus:
Replace oil boiler and all tanks with condensing gas combi.
Leave crappy water supply of 15mm as is - (11 litres per minute) and
plumb
it to all kitchen equipment - sink, dishwasher etc.
Bring in new 35mm water supply and plumb all "upstairs" stuff with new
water
supply through combi (and kitchen hot tap). Will feed 2 loos, 2 showers
and
1 bath.
This is after friendly plumber's advice that just upgrading the supply as
is
mightn't be enough for our needs as a family of five.
Combi will do CH and one large underfloor heating area and bathroom
stuff.


My only concern here is whether even a large combi is going to give
you a fast enough production rate of hot water if you want to use the
showers and bath simultaneously.

Consider that in effect in cold weather the specified flow rate of the
combi will be all that you will get at shower temperature. If the
mains supply is (say) 8 degrees and the shower 40, then at the
standard 35 degree uplift temperature by the boiler you will not be
mixing much cold in with this and the combi flow rate becomes the
total rate.

Check out the flows that you want for the showers (personally I
wouldn't accept less than 15 litres/min each) plus the bath and you
may be in trouble with a combi - even a large one.

The Screwfix Pressure Balance Shower Valve is rated at 7 litres/min, and
that is mixed water, so drawing less from the combi than 7 litres/min. Most
showers are around this. This makes a 13 litre/min combi adequate for two
simultaneous showers.

In this case, as liberating space is important, two combi's might be the
best approach. One large (13 litres/min), for the bath, and one smaller,
around 10 litres/min.

You may find that you need to have some form of heat storage, whether
it be a pressurised cylinder or a heatbank. There is nothing to
stop you heating one of these from a combi using its CH side and
motorised valves (effectively like a non-combi), then using the hot
water production from the combi to run some of the hot water services
and the stored water the rest.....



---
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Suz wrote:

"Grunff" wrote in message
...

Suz wrote:


Replace oil boiler and all tanks with condensing gas combi.

But why? Oil is cheaper and (IMO) nicer to work with. Why do you
want to switch to gas?


We have been advised by a few different un-involved parties that the gas
bills are lower over time.


Do the cost benefit analyis on the comparison betwen yiour existing oil
suply and teh coast of re-rouetng things.

Amortizing over the time you expect to spend in the house.

Unforgetattble anecdote. Bloke turns up at garage with 5.7

liter V8 american muscle car and proceeds to fill up..


"Blimey you should get a porcshe, just as fast and half the petrol cost"
"Posrches costs £50 grand, I picked this up for five. £45 grand buys a
LOT of petrol"


The oil boiler is getting on a bit and needs something done soon It is
housed in a like brick ediface that is right where the kitchen extension
will go . This will not be needed if we change it's location to
understairs . Getting shot of the hot tank means we can have a separate
bath and shower in the main bathroom We want to do a roof space
conversion and it would be great to get rid of the tanks up there. All
this will be replaced by one boiler in the big understairs cupboard which
just hordes junk at the mo. And the natural gas conduit is already laid
under the new drive The oil boiler had a spill over it a couple of years
ago and it *stinks*. Not nice to work with (sadly shakes head), won't be
sorry to see it go .

More than



Well. If you are going the full Monty so to speak, I'd go for a full
mains pressure system and a BIG hot water tank, and rip out all those
silly header tanks and stuff, and put in the biggest oil or gas system
boiler you can.

Unless youyr energy requirements are huge, in which case burn the
teenage daighters and insulate the house with what you will save, the
difference between gas and oil is not AFAICR so marked as to make it the
dominant cost - best to look for cheapest installation costs IMHO.

IMM likes combis. I don't. I like mains pressure hot water systems. Each
has its points, but on a larger installation I prefer to have some kind
of hot water tank to cope with peak demands. Adding things to combis
defeats the main advantage - CHEAP, with no hot water tank.


I stuck my HW tank in the roof. That's the only tank I have. There is
still plenty of room for other stuff up there.

IF you are willing to trade the little space used by sealed hot water
tank and teh added expense of one for the almost unlimited availability
of lashings of hot water (and its amazing how much you need when you are
doing the washing, kids/visitors having showers, other half running a
bath on a saturday morning) then mains pressure would suit. If you
arereally tight or space, on a limited budget and only have one
bathroom, then combi is good enough.

As far as gas v oil goes - toss a coin, or add up total costs. I don;t
have any access to gas so it was a no brainer. If I had had gas, I'd
probably have used it. I definitely would have, for cooking.

Yopu can lay oil an water pipes anywhere you want, as long as the total
pipe run isn't too long n teh case of oil, and the pipe diameter is
adequate in the case of water. Practical considerations of waht is
easiest to dig up dictate things usually.

I have no experience of gas, so won't comment.


Suzanne

"Suz" wrote
| "Grunff" wrote
| Replace oil boiler and all tanks with condensing gas combi.
| But why? Oil is cheaper and (IMO) nicer to work with. Why do you
| want to switch to gas?
| We have been advised by a few different un-involved parties that the gas
| bills are lower over time.

Also, no unsightly oil tank in the garden, and IMHO gas ch is more appealing
to house buyers than any other type. I'm not saying it will add £1000s to
the property compared to oil, but oil ch can be viewed as a slight drawback
by some prospective purchasers because of the tank/smell/refilling - even if
the energy itself is a bit cheaper.

Owain

This is after friendly plumber's advice that just upgrading the supply
as
is
mightn't be enough for our needs as a family of five.

35mm will not be enough? See the water company, and see what they will
deliver in flow and pressure.

No he meant one supply of 15mm would not be enough and to put in a 35mm in
addition. Pressure is 5bar and flow rate with current old 15mm supply is
11litres a minute

Combi will do CH and one large underfloor heating area and bathroom
stuff.

Big story, one small question:
To avoid digging up lovely new tarmac drive, we would like to bring it
through grass to near the front door and then dig across paved step area
which would be relatively simple to re-lay, in under door area and
straight
up the hall (needs levelled anyway to tile, its like a dog's hind leg at
mo). But can we? Is it silly to bring 35mm water supply through a
hallway
in case of leaks etc? Is it stupid to put a gradual bend in the pipe
just
to save a drive?

No it is not. See the water company first. Some only allow the shortest
route from the water mains to the house.

The route won't be a problem as main connection is over the hedge at the
point where grass meets driveway :-), just a groovy swerve at the bit near
the door. Apparently it is our responsibility to choose route, they just
inspect it to give it the OK


If you are bringing in a new 35mm water main, then why are you leaving the
existing 15mm main? The water company will charge you extra for two mains
entering a property. 35mm will be fine, assuming you will have the
pressure
and flow, which most 35mm pipes do. See the water company.

We thought we would leave the existing one and all the internal plumbing to
kitchen stuff intact so there would be no unexpected dip in pressure from
dishwasher etc.
It would be a one off installation charge for new main of just over £100 at
the mains (plus our costs of installation on our side). We do not have
water charges in Belfast :-), just terrorists and stuff.


2 showers, one bath, 5 people. I would go for a heat bank and a gas
condensing boiler. See Christian McArdles posting on the current thread
Hot
water System. He has bought a new DPS Pandora heat bank and is fitting
it
in his loft. The same price as a Megaflow unvented cylinder and no
overflows. This will do all you want in a hot water mains pressure system
and no cold water storage tank. Then fit a condensing boiler. The UFH
side
is easy enough. See the Polyplumb or Speedfit web sites.
http://ww.heatweb.com

A combi will do what you want, but it will be a top of the range
state-of-the-art very expensive job. It may work out cheaper though and
you
save space.

Yes fit the Mira 415 shower, or the Screwfix job - I posted the details.
I
fitted a 415 for a friend 13 years ago. I have used it occasionally and
it
operates very well. It reacts very quick to pressure fluctuations in the
system. You notice a pressure change rather than a temperature change.

Another suggestion will be to install a pressure equalising valve at the
main stop cock. One pie directly to a heat bank, or combi, and the other,
to the cold outlets. Then cheaper shower mixers can be used. The
equalisation valve will do all the house, inc the two showers. You will
have to price up two 415s and two shower mixers and a 22mm equalisation
valve. The valves are available from Plumb Center.

Will the pressure equalising valve reduce the flowrate at all?

"Suz" wrote in message
...
This is after friendly plumber's advice that just upgrading the supply
as
is
mightn't be enough for our needs as a family of five.

35mm will not be enough? See the water company, and see what they will
deliver in flow and pressure.

No he meant one supply of 15mm would not be enough and to put in a 35mm in
addition. Pressure is 5bar and flow rate with current old 15mm supply is
11litres a minute

Combi will do CH and one large underfloor heating area and bathroom
stuff.

Big story, one small question:
To avoid digging up lovely new tarmac drive, we would like to bring it
through grass to near the front door and then dig across paved step
area
which would be relatively simple to re-lay, in under door area and
straight
up the hall (needs levelled anyway to tile, its like a dog's hind leg
at
mo). But can we? Is it silly to bring 35mm water supply through a
hallway
in case of leaks etc? Is it stupid to put a gradual bend in the pipe
just
to save a drive?

No it is not. See the water company first. Some only allow the
shortest
route from the water mains to the house.

The route won't be a problem as main connection is over the hedge at the
point where grass meets driveway :-), just a groovy swerve at the bit near
the door. Apparently it is our responsibility to choose route, they just
inspect it to give it the OK


If you are bringing in a new 35mm water main, then why are you leaving
the
existing 15mm main? The water company will charge you extra for two
mains
entering a property. 35mm will be fine, assuming you will have the
pressure
and flow, which most 35mm pipes do. See the water company.

We thought we would leave the existing one and all the internal plumbing
to
kitchen stuff intact so there would be no unexpected dip in pressure from
dishwasher etc.
It would be a one off installation charge for new main of just over £100
at
the mains (plus our costs of installation on our side). We do not have
water charges in Belfast :-), just terrorists and stuff.


2 showers, one bath, 5 people. I would go for a heat bank and a gas
condensing boiler. See Christian McArdles posting on the current thread
Hot
water System. He has bought a new DPS Pandora heat bank and is fitting
it
in his loft. The same price as a Megaflow unvented cylinder and no
overflows. This will do all you want in a hot water mains pressure
system
and no cold water storage tank. Then fit a condensing boiler. The UFH
side
is easy enough. See the Polyplumb or Speedfit web sites.
http://ww.heatweb.com

A combi will do what you want, but it will be a top of the range
state-of-the-art very expensive job. It may work out cheaper though and
you
save space.

Yes fit the Mira 415 shower, or the Screwfix job - I posted the details.
I
fitted a 415 for a friend 13 years ago. I have used it occasionally and
it
operates very well. It reacts very quick to pressure fluctuations in
the
system. You notice a pressure change rather than a temperature change.

Another suggestion will be to install a pressure equalising valve at the
main stop cock. One pie directly to a heat bank, or combi, and the
other,
to the cold outlets. Then cheaper shower mixers can be used. The
equalisation valve will do all the house, inc the two showers. You will
have to price up two 415s and two shower mixers and a 22mm equalisation
valve. The valves are available from Plumb Center.

Will the pressure equalising valve reduce the flowrate at all?

No. the hot and cold supplies go through it. The hot supply can be on the
cold feed side of a combi, unvented cylinder or heat bank. when one side of
the valve drops in pressure (someone draws-off cold water) the other side
drops its pressure to suit, so it is equalised. some are built into shower
mixers, some hare 15mm and are to be fitted before a mixer, others are 22mm
and are to be fitted at the stop-cock (one leg to all cold taps the other
supplies the hot water appliance).




---
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Version: 6.0.524 / Virus Database: 321 - Release Date: 06/10/2003

"Andy Hall" wrote in message
...
On Tue, 7 Oct 2003 23:06:10 +0100, "Suz" wrote:

Still chewing over with hubby what way to do CH and DWS.

Learnt a lot from all of you boys in the last few weeks - thanks.
Reading
with interest the "Thermostatic or electric shower from combi" thread
posted
by Eno. Makes a lot more sense when you understand the terms without a
dictionary of gas and plumbing terms!

The latest brainstorm from us is thus:
Replace oil boiler and all tanks with condensing gas combi.
Leave crappy water supply of 15mm as is - (11 litres per minute) and
plumb
it to all kitchen equipment - sink, dishwasher etc.
Bring in new 35mm water supply and plumb all "upstairs" stuff with new
water
supply through combi (and kitchen hot tap). Will feed 2 loos, 2 showers
and
1 bath.
This is after friendly plumber's advice that just upgrading the supply as
is
mightn't be enough for our needs as a family of five.
Combi will do CH and one large underfloor heating area and bathroom
stuff.


My only concern here is whether even a large combi is going to give
you a fast enough production rate of hot water if you want to use the
showers and bath simultaneously.

Yes, and my comment is "no point in having 2 bathrooms if you don't intend
to use them both at the same time"

Consider that in effect in cold weather the specified flow rate of the
combi will be all that you will get at shower temperature. If the
mains supply is (say) 8 degrees and the shower 40, then at the
standard 35 degree uplift temperature by the boiler you will not be
mixing much cold in with this and the combi flow rate becomes the
total rate.

Check out the flows that you want for the showers (personally I
wouldn't accept less than 15 litres/min each) plus the bath and you
may be in trouble with a combi - even a large one.

We had considered putting an electric shower in for the girls and hogging a
brilliant one for ourselves, but we reckoned they would just hijack ours
when they grow up.

You may find that you need to have some form of heat storage, whether
it be a pressurised cylinder or a heatbank. There is nothing to
stop you heating one of these from a combi using its CH side and
motorised valves (effectively like a non-combi), then using the hot
water production from the combi to run some of the hot water services
and the stored water the rest.....

We have been looking at the Megoflo brochure.

A couple of questions came out of this:
Is it not a waste of energy to have hot water stored and therefore lose
heat/energy before it gets used?
If you are having a shower and hot water gets drawn off somewhere else, do
you get frozen in the shower?

"Suz" wrote in message
...

"Andy Hall" wrote in message
...
On Tue, 7 Oct 2003 23:06:10 +0100, "Suz" wrote:

Still chewing over with hubby what way to do CH and DWS.

Learnt a lot from all of you boys in the last few weeks - thanks.
Reading
with interest the "Thermostatic or electric shower from combi" thread
posted
by Eno. Makes a lot more sense when you understand the terms without a
dictionary of gas and plumbing terms!

The latest brainstorm from us is thus:
Replace oil boiler and all tanks with condensing gas combi.
Leave crappy water supply of 15mm as is - (11 litres per minute) and
plumb
it to all kitchen equipment - sink, dishwasher etc.
Bring in new 35mm water supply and plumb all "upstairs" stuff with new
water
supply through combi (and kitchen hot tap). Will feed 2 loos, 2
showers
and
1 bath.
This is after friendly plumber's advice that just upgrading the supply
as
is
mightn't be enough for our needs as a family of five.
Combi will do CH and one large underfloor heating area and bathroom
stuff.


My only concern here is whether even a large combi is going to give
you a fast enough production rate of hot water if you want to use the
showers and bath simultaneously.

Yes, and my comment is "no point in having 2 bathrooms if you don't intend
to use them both at the same time"

Consider that in effect in cold weather the specified flow rate of the
combi will be all that you will get at shower temperature. If the
mains supply is (say) 8 degrees and the shower 40, then at the
standard 35 degree uplift temperature by the boiler you will not be
mixing much cold in with this and the combi flow rate becomes the
total rate.

Check out the flows that you want for the showers (personally I
wouldn't accept less than 15 litres/min each) plus the bath and you
may be in trouble with a combi - even a large one.

We had considered putting an electric shower in for the girls and hogging
a
brilliant one for ourselves, but we reckoned they would just hijack ours
when they grow up.

You may find that you need to have some form of heat storage, whether
it be a pressurised cylinder or a heatbank. There is nothing to
stop you heating one of these from a combi using its CH side and
motorised valves (effectively like a non-combi), then using the hot
water production from the combi to run some of the hot water services
and the stored water the rest.....

We have been looking at the Megoflo brochure.

Give unvented cylinders a wide berth. Go for a heat bank. Look at the
current thread about the Pandora. About the same price.

A couple of questions came out of this:
Is it not a waste of energy to have hot water stored and therefore lose
heat/energy before it gets used?

In theory yes. But the heat looses are not that great.

If you are having a shower and hot water gets drawn off somewhere else, do
you get frozen in the shower?

It depends on the flow rate of the heat bank, combi etc. Installing
equalising valves reduces influences from one draw-off to the other. Also
having large enough pipes and splitting them to hot and cold after the mains
stopcock helps.




---
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Owain wrote:

"Suz" wrote
| "Grunff" wrote
| Replace oil boiler and all tanks with condensing gas combi.
| But why? Oil is cheaper and (IMO) nicer to work with. Why do you
| want to switch to gas?
| We have been advised by a few different un-involved parties that the gas
| bills are lower over time.

Also, no unsightly oil tank in the garden, and IMHO gas ch is more appealing
to house buyers than any other type. I'm not saying it will add £1000s to
the property compared to oil, but oil ch can be viewed as a slight drawback
by some prospective purchasers because of the tank/smell/refilling - even if
the energy itself is a bit cheaper.



My tank don't smell, is a cinch to reill, and is nor covered with
attractive climbing roses and creepers.


Owain

On Wed, 8 Oct 2003 10:16:02 +0100, "IMM" wrote:


"Andy Hall" wrote in message
.. .


Check out the flows that you want for the showers (personally I
wouldn't accept less than 15 litres/min each) plus the bath and you
may be in trouble with a combi - even a large one.

The Screwfix Pressure Balance Shower Valve is rated at 7 litres/min, and
that is mixed water, so drawing less from the combi than 7 litres/min. Most
showers are around this. This makes a 13 litre/min combi adequate for two
simultaneous showers.

It would do if you think that 7 litres/min for one was good enough.
I don't. This is not much better than a crappy electric job.



---

..andy

To email, substitute .nospam with .gl

"Andy Hall" wrote in message
...
On Wed, 8 Oct 2003 10:16:02 +0100, "IMM" wrote:


"Andy Hall" wrote in message
.. .


Check out the flows that you want for the showers (personally I
wouldn't accept less than 15 litres/min each) plus the bath and you
may be in trouble with a combi - even a large one.

The Screwfix Pressure Balance Shower Valve is rated at 7 litres/min, and
that is mixed water, so drawing less from the combi than 7 litres/min.
Most
showers are around this. This makes a 13 litre/min combi adequate for
two
simultaneous showers.

It would do if you think that 7 litres/min for one was good enough.
I don't. This is not much better than a crappy electric job.

There is a big difference between 4 litres/min and 7 litres/min. I'm sure
this mixer can take more than 7 litres/min though.





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On Wed, 8 Oct 2003 16:48:03 +0100, "Suz" wrote:




Yes, and my comment is "no point in having 2 bathrooms if you don't intend
to use them both at the same time"

Exaactly.


Consider that in effect in cold weather the specified flow rate of the
combi will be all that you will get at shower temperature. If the
mains supply is (say) 8 degrees and the shower 40, then at the
standard 35 degree uplift temperature by the boiler you will not be
mixing much cold in with this and the combi flow rate becomes the
total rate.

Check out the flows that you want for the showers (personally I
wouldn't accept less than 15 litres/min each) plus the bath and you
may be in trouble with a combi - even a large one.

We had considered putting an electric shower in for the girls and hogging a
brilliant one for ourselves, but we reckoned they would just hijack ours
when they grow up.

Electric showers are very disappointing. 5 litres/min if you are
lucky. They won't thank you for that when they are washing their
hair I can promise you.

As to hijacking, I can confirm that they will hijack both and will
leave both in a condition other than that in which they would hope to
find it.

They are great at hanging up the clothes that you just washed as well
- until they run out of floor space.

A permanent supply of bin liners is essential while they go through
the teenage metamorphosis.



You may find that you need to have some form of heat storage, whether
it be a pressurised cylinder or a heatbank. There is nothing to
stop you heating one of these from a combi using its CH side and
motorised valves (effectively like a non-combi), then using the hot
water production from the combi to run some of the hot water services
and the stored water the rest.....

We have been looking at the Megoflo brochure.

A couple of questions came out of this:
Is it not a waste of energy to have hot water stored and therefore lose
heat/energy before it gets used?

Not really. If you have good insulation the heat loss becomes tens
of watts - i.e. less than a light bulb.


If you are having a shower and hot water gets drawn off somewhere else, do
you get frozen in the shower?

Not if the plumbing is designed properly. If you have either a
stored hot water system where the water is used directly, having been
heated to 60 degrees, or a heatbank where it is hotter, but the stored
water is used indirectly through a heat exchanger then you are rather
better isolated from the effects of temperature change in the cold
water affecting the hot water production rate.

If you mix 60 degree hot water with some cold to produce 40 degree
water for a shower, even if the cold water temperature varies over the
year the effect is not as great as if you are using a combi and *all*
of its production is used for the shower. Then you would be
vulnerable. This is one reason why IMM is suggesting that two combis
might be an option. The peak needs might not be met by one.

Having some form of storage would improve the overall system
performance considerably - whether it's a pressurised cylinder or a
heat bank.



..andy

To email, substitute .nospam with .gl

"Andy Hall" wrote in message
...
On Wed, 8 Oct 2003 16:48:03 +0100, "Suz" wrote:




Yes, and my comment is "no point in having 2 bathrooms if you don't
intend
to use them both at the same time"

Exaactly.


Consider that in effect in cold weather the specified flow rate of the
combi will be all that you will get at shower temperature. If the
mains supply is (say) 8 degrees and the shower 40, then at the
standard 35 degree uplift temperature by the boiler you will not be
mixing much cold in with this and the combi flow rate becomes the
total rate.

Check out the flows that you want for the showers (personally I
wouldn't accept less than 15 litres/min each) plus the bath and you
may be in trouble with a combi - even a large one.

We had considered putting an electric shower in for the girls and hogging
a
brilliant one for ourselves, but we reckoned they would just hijack ours
when they grow up.

Electric showers are very disappointing. 5 litres/min if you are
lucky. They won't thank you for that when they are washing their
hair I can promise you.

As to hijacking, I can confirm that they will hijack both and will
leave both in a condition other than that in which they would hope to
find it.

They are great at hanging up the clothes that you just washed as well
- until they run out of floor space.

A permanent supply of bin liners is essential while they go through
the teenage metamorphosis.



You may find that you need to have some form of heat storage, whether
it be a pressurised cylinder or a heatbank. There is nothing to
stop you heating one of these from a combi using its CH side and
motorised valves (effectively like a non-combi), then using the hot
water production from the combi to run some of the hot water services
and the stored water the rest.....

We have been looking at the Megoflo brochure.

A couple of questions came out of this:
Is it not a waste of energy to have hot water stored and therefore lose
heat/energy before it gets used?

Not really. If you have good insulation the heat loss becomes tens
of watts - i.e. less than a light bulb.


If you are having a shower and hot water gets drawn off somewhere else,
do
you get frozen in the shower?

Not if the plumbing is designed properly. If you have either a
stored hot water system where the water is used directly, having been
heated to 60 degrees, or a heatbank where it is hotter, but the stored
water is used indirectly through a heat exchanger then you are rather
better isolated from the effects of temperature change in the cold
water affecting the hot water production rate.

If you mix 60 degree hot water with some cold to produce 40 degree
water for a shower, even if the cold water temperature varies over the
year the effect is not as great as if you are using a combi and *all*
of its production is used for the shower. Then you would be
vulnerable. This is one reason why IMM is suggesting that two combis
might be an option. The peak needs might not be met by one.

Having some form of storage would improve the overall system
performance considerably - whether it's a pressurised cylinder or a
heat bank.

Or two combi's. Liberating space is one aim here. Combi's neatly fix to
walls. Unless a heat bank is designed to be square and sit at the bottom of
a cupboard taking up little space. Long thin cylinders take up space.



---
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On Wed, 8 Oct 2003 22:29:56 +0100, "IMM" wrote:


"Andy Hall" wrote in message
.. .
On Wed, 8 Oct 2003 10:16:02 +0100, "IMM" wrote:


"Andy Hall" wrote in message
.. .


Check out the flows that you want for the showers (personally I
wouldn't accept less than 15 litres/min each) plus the bath and you
may be in trouble with a combi - even a large one.

The Screwfix Pressure Balance Shower Valve is rated at 7 litres/min, and
that is mixed water, so drawing less from the combi than 7 litres/min.
Most
showers are around this. This makes a 13 litre/min combi adequate for
two
simultaneous showers.

It would do if you think that 7 litres/min for one was good enough.
I don't. This is not much better than a crappy electric job.

There is a big difference between 4 litres/min and 7 litres/min. I'm sure
this mixer can take more than 7 litres/min though.


There's a big difference between 50p and a pound as well, but neither
will buy a large G&T........ :-)









---

..andy

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