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Lagging boiler hot water delivery/supply
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AnthonyL
Oct 30, 2022, 4:45:04 AM10/30/22
to
Should the cold water supply and the hot water delivery be wrapped up
together?
I'm working in the mainly boarded loft (bungalow) and have uncovered
some of the boxing/platform under which the pipes run. The boxing
sits about 5" above the joists and is insulated.
The supply and delivery 1/2" pipes run about 20m from the front of the
house to the back and are next to eachother. The lagging, felt I
think, seems to be wrapped around the outside of the pipes rather than
around the pipes individually.
The hot water takes a long time to come through to the kitchen and I
wonder if it is spending heat warming the cold water next to it.
Whilst I can see some advantage in effectively pre-heating if the
demand is for a lot of water, it would seem to be counter productive
if just a small amount of hot water is needed.
--
AnthonyL
Why ever wait to finish a job before starting the next?
together?
I'm working in the mainly boarded loft (bungalow) and have uncovered
some of the boxing/platform under which the pipes run. The boxing
sits about 5" above the joists and is insulated.
The supply and delivery 1/2" pipes run about 20m from the front of the
house to the back and are next to eachother. The lagging, felt I
think, seems to be wrapped around the outside of the pipes rather than
around the pipes individually.
The hot water takes a long time to come through to the kitchen and I
wonder if it is spending heat warming the cold water next to it.
Whilst I can see some advantage in effectively pre-heating if the
demand is for a lot of water, it would seem to be counter productive
if just a small amount of hot water is needed.
--
AnthonyL
Why ever wait to finish a job before starting the next?
Brian Gaff
Oct 30, 2022, 4:53:48 AM10/30/22
to
More likely that the water in the pipe will always be cold unless its been
run off. I suppose the idea of warming the cold a bit would make some
difference but maybe it was done to stop it freezing?
Brian
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"AnthonyL" <nos...@please.invalid> wrote in message
news:635e34c9....@news.eternal-september.org...
run off. I suppose the idea of warming the cold a bit would make some
difference but maybe it was done to stop it freezing?
Brian
--
--:
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...
bri...@blueyonder.co.uk
Blind user, so no pictures please
Note this Signature is meaningless.!
"AnthonyL" <nos...@please.invalid> wrote in message
news:635e34c9....@news.eternal-september.org...
Theo
Oct 30, 2022, 5:12:41 AM10/30/22
to
AnthonyL <nos...@please.invalid> wrote:
> Should the cold water supply and the hot water delivery be wrapped up
> together?
I suspect it's probably been lagged for frost protection - ie keep the cold
> Should the cold water supply and the hot water delivery be wrapped up
> together?
out of both pipes - rather than efficiency. That does nothing the other 99%
of the year - in fact likely makes it worse. Better to individually
insulate the pipes so they are frost protected and the hot water stays hot.
How much space is there between the two pipes? Enough to squeeze in some
foam insulation around each pipe?
This stuff is good (also good at noise dampening):
https://www.jtmplumbing.co.uk/insulation-c555/armacell-armaflex-class-o-selfseal-pipe-insulation-c204
while this is cheaper but better than nothing:
https://www.jtmplumbing.co.uk/insulation-c555/climaflex-polyethylene-pipe-insulation-c556
(you probably want the pre-slit version which I can't seem to find on that
site)
General rule of thumb is to install the pipe diameter's thickness of
insulation, but often there's not space for that so you have to compromise.
The nitrile Armaflex is self adhesive so just slips around the pipe and
sticks to itself, while the polyethylene needs exterior fixings (eg tape or
cable ties).
Theo
Martin Brown
Oct 30, 2022, 5:38:11 AM10/30/22
to
On 30/10/2022 08:44, AnthonyL wrote:
> Should the cold water supply and the hot water delivery be wrapped up
> together?
In an ideal world no. But the main effect of having the pipes too close
> Should the cold water supply and the hot water delivery be wrapped up
> together?
together is that after running hot water you end up with a cold pipe
that is full of lukewarm water for some time afterwards.
>
> I'm working in the mainly boarded loft (bungalow) and have uncovered
> some of the boxing/platform under which the pipes run. The boxing
> sits about 5" above the joists and is insulated.
>
> The supply and delivery 1/2" pipes run about 20m from the front of the
> house to the back and are next to eachother. The lagging, felt I
> think, seems to be wrapped around the outside of the pipes rather than
> around the pipes individually.
A bit of insulation between them would help keep your cold water pipe
> I'm working in the mainly boarded loft (bungalow) and have uncovered
> some of the boxing/platform under which the pipes run. The boxing
> sits about 5" above the joists and is insulated.
>
> The supply and delivery 1/2" pipes run about 20m from the front of the
> house to the back and are next to eachother. The lagging, felt I
> think, seems to be wrapped around the outside of the pipes rather than
> around the pipes individually.
colder. Unless it bothers you I wouldn't bother disturbing them unless
you are already doing some other work up there.
> The hot water takes a long time to come through to the kitchen and I
> wonder if it is spending heat warming the cold water next to it.
> Whilst I can see some advantage in effectively pre-heating if the
> demand is for a lot of water, it would seem to be counter productive
> if just a small amount of hot water is needed.
long pipe with hot water. There are some losses to the cold copper pipe
it is in but losses to the adjacent pipe assuming it is not in direct
contact with the hot pipe will be on the timescale of 10s of minutes.
Hotels have a circulating loop for hot water with short drop legs from
the main pipe loop. Much more lossy but near instant hot water.
--
Regards,
Martin Brown
Theo
Oct 30, 2022, 6:15:55 AM10/30/22
to
Martin Brown <'''newspam'''@nonad.co.uk> wrote:
> No. That is just the distance the water has to flow before it fills the
> long pipe with hot water. There are some losses to the cold copper pipe
> it is in but losses to the adjacent pipe assuming it is not in direct
> contact with the hot pipe will be on the timescale of 10s of minutes.
I think the goal here would be to insulate the hot pipe so it stays hot.
> No. That is just the distance the water has to flow before it fills the
> long pipe with hot water. There are some losses to the cold copper pipe
> it is in but losses to the adjacent pipe assuming it is not in direct
> contact with the hot pipe will be on the timescale of 10s of minutes.
Then more of the time you're running hot water that's in the pipe, rather
than waiting for hot water to come all the way from the far end. Where it
loses heat to is irrelevant, just that you have to run all that lukewarm
water out before it turns out. If the run is long, that time can be
significant (and water wasted significant too).
A second thing is if you want cold water for eg drinking water, and that
causes you to run the tap until it goes cold. In that case, insulating the
cold will keep that colder. If you aren't so bothered by it being cold (eg
in a bathroom) then you might decide not to insulate the cold.
As long as there is some insulation around both pipes they'll be frost
protected - doesn't matter if it's together or separately.
> Hotels have a circulating loop for hot water with short drop legs from
> the main pipe loop. Much more lossy but near instant hot water.
you turned on the tap or shower at 3am you could have to run it for quite a
long time to get hot water from the tank.
Theo
AnthonyL
Oct 30, 2022, 6:33:24 AM10/30/22
to
>
Thanks Theo and Martin.
I've had a closer look - see https://flic.kr/p/2nW3pYo
Seems as if the delivery pipe is 1/2" (and earthed) and the return
pipe presumably 3/4" which I calcuate to be 5.7L. That's over a
gallon before any warmth comes through.
As can be seen the pipes are close together but not touching, and
there are two spirals of felt wrapping. It cannot be cost effective
to try and replace the approx 15m length I can more or less readily
get to.
Just trying to improve the loft insulation brings home how expensive
and time consuming the exercise is when not done as part of original
build.
At the top of the picture can be seen the original loose insulation
which is going to get rolls of 200mm insulation laid over. I think
any electrics should as far as possible be over the insulation.
>Hotels have a circulating loop for hot water with short drop legs from
>the main pipe loop. Much more lossy but near instant hot water.
>
appealing as the idea is.
AnthonyL
Oct 30, 2022, 6:38:55 AM10/30/22
to
On 30 Oct 2022 10:15:49 +0000 (GMT), Theo
quite sparse with running the hot water back to the kitchen I don't
think we encounter cold water that is not cold, additionally the
kitchen cold water tap is directly above the water meter.
<theom...@chiark.greenend.org.uk> wrote:
>Martin Brown <'''newspam'''@nonad.co.uk> wrote:
>> No. That is just the distance the water has to flow before it fills the
>> long pipe with hot water. There are some losses to the cold copper pipe
>> it is in but losses to the adjacent pipe assuming it is not in direct
>> contact with the hot pipe will be on the timescale of 10s of minutes.
>
>I think the goal here would be to insulate the hot pipe so it stays hot.
>Then more of the time you're running hot water that's in the pipe, rather
>than waiting for hot water to come all the way from the far end. Where it
>loses heat to is irrelevant, just that you have to run all that lukewarm
>water out before it turns out. If the run is long, that time can be
>significant (and water wasted significant too).
>
>A second thing is if you want cold water for eg drinking water, and that
>causes you to run the tap until it goes cold. In that case, insulating the
>cold will keep that colder. If you aren't so bothered by it being cold (eg
>in a bathroom) then you might decide not to insulate the cold.
>
The cold water feed is just to the boiler and utility room. As we are
>Martin Brown <'''newspam'''@nonad.co.uk> wrote:
>> No. That is just the distance the water has to flow before it fills the
>> long pipe with hot water. There are some losses to the cold copper pipe
>> it is in but losses to the adjacent pipe assuming it is not in direct
>> contact with the hot pipe will be on the timescale of 10s of minutes.
>
>I think the goal here would be to insulate the hot pipe so it stays hot.
>Then more of the time you're running hot water that's in the pipe, rather
>than waiting for hot water to come all the way from the far end. Where it
>loses heat to is irrelevant, just that you have to run all that lukewarm
>water out before it turns out. If the run is long, that time can be
>significant (and water wasted significant too).
>
>A second thing is if you want cold water for eg drinking water, and that
>causes you to run the tap until it goes cold. In that case, insulating the
>cold will keep that colder. If you aren't so bothered by it being cold (eg
>in a bathroom) then you might decide not to insulate the cold.
>
quite sparse with running the hot water back to the kitchen I don't
think we encounter cold water that is not cold, additionally the
kitchen cold water tap is directly above the water meter.
Theo
Oct 30, 2022, 6:50:41 AM10/30/22
to
AnthonyL <nos...@please.invalid> wrote:
> Thanks Theo and Martin.
>
> I've had a closer look - see https://flic.kr/p/2nW3pYo
>
> Seems as if the delivery pipe is 1/2" (and earthed) and the return
> pipe presumably 3/4" which I calcuate to be 5.7L. That's over a
> gallon before any warmth comes through.
>
> As can be seen the pipes are close together but not touching, and
> there are two spirals of felt wrapping. It cannot be cost effective
> to try and replace the approx 15m length I can more or less readily
> get to.
If you wanted to improve things, what I'd think about is getting some
> Thanks Theo and Martin.
>
> I've had a closer look - see https://flic.kr/p/2nW3pYo
>
> Seems as if the delivery pipe is 1/2" (and earthed) and the return
> pipe presumably 3/4" which I calcuate to be 5.7L. That's over a
> gallon before any warmth comes through.
>
> As can be seen the pipes are close together but not touching, and
> there are two spirals of felt wrapping. It cannot be cost effective
> to try and replace the approx 15m length I can more or less readily
> get to.
plastic barrier pipe (PEX or polybutylene; PB is more flexible), putting
some Armaflex insulation on it (the full-round stuff can be slipped over the
cut end of the new pipe avoiding having to seal along each length), and then
splicing it into the existing heating pipe at each end. Then your old pipe
run carries just the cold and an empty old hot pipe, with sufficient lagging
for frost purposes. And now you have a well insulated new hot water run.
Because it's flexible it's easier to run wherever you want without having to
disturb too much other stuff.
Theo
Andrew
Oct 30, 2022, 7:33:21 AM10/30/22
to
Ideally it should be as close to the point of use as
possible, and normally in the kitchen, with the bathroom
immediately above.
Some makes also have a (not very) eco setting whereby
it learns your usage patterns and keeps it internal
heat exchanger hot.
Separate lagging might be a good idea if it is a
combi and if your mains pressure is good enough even
replacing a long run of hot 15mm pipe to the kitchen
(with a tee junction for the bathroom) with 2
separate 10mm hot water feeds to the kitchen and
bathroom would reduce the delay.
Martin Brown
Oct 30, 2022, 8:15:27 AM10/30/22
to
On 30/10/2022 10:33, AnthonyL wrote:
> On Sun, 30 Oct 2022 09:38:06 +0000, Martin Brown
> <'''newspam'''@nonad.co.uk> wrote:
>
>> On 30/10/2022 08:44, AnthonyL wrote:
>>> The hot water takes a long time to come through to the kitchen and I
>>> wonder if it is spending heat warming the cold water next to it.
>>> Whilst I can see some advantage in effectively pre-heating if the
>>> demand is for a lot of water, it would seem to be counter productive
>>> if just a small amount of hot water is needed.
>>
>> No. That is just the distance the water has to flow before it fills the
>> long pipe with hot water. There are some losses to the cold copper pipe
>> it is in but losses to the adjacent pipe assuming it is not in direct
>> contact with the hot pipe will be on the timescale of 10s of minutes.
>
> Not fully sure I understand "10s of minutes"
That's about how long it takes for heat transfer through air from one
> On Sun, 30 Oct 2022 09:38:06 +0000, Martin Brown
> <'''newspam'''@nonad.co.uk> wrote:
>
>> On 30/10/2022 08:44, AnthonyL wrote:
>>> The hot water takes a long time to come through to the kitchen and I
>>> wonder if it is spending heat warming the cold water next to it.
>>> Whilst I can see some advantage in effectively pre-heating if the
>>> demand is for a lot of water, it would seem to be counter productive
>>> if just a small amount of hot water is needed.
>>
>> No. That is just the distance the water has to flow before it fills the
>> long pipe with hot water. There are some losses to the cold copper pipe
>> it is in but losses to the adjacent pipe assuming it is not in direct
>> contact with the hot pipe will be on the timescale of 10s of minutes.
>
> Not fully sure I understand "10s of minutes"
pipe to the other. Your pipe run looks a bit close together to me and
with old style wrap around lagging. Glass fibre? Wear a dust mask and
gloves it is itchy as hell if you touch it and much worse to breathe!
> I've had a closer look - see https://flic.kr/p/2nW3pYo
>
> Seems as if the delivery pipe is 1/2" (and earthed) and the return
> pipe presumably 3/4" which I calcuate to be 5.7L. That's over a
> gallon before any warmth comes through.
>
> As can be seen the pipes are close together but not touching, and
> there are two spirals of felt wrapping. It cannot be cost effective
> to try and replace the approx 15m length I can more or less readily
> get to.
>
> Just trying to improve the loft insulation brings home how expensive
> and time consuming the exercise is when not done as part of original
> build.
can find it get the stuff that is wrapped in a thin foil on one side bag
to minimise your contact even with the modern rockwool. Shiny side up.
>
> At the top of the picture can be seen the original loose insulation
> which is going to get rolls of 200mm insulation laid over. I think
> any electrics should as far as possible be over the insulation.
>
>> Hotels have a circulating loop for hot water with short drop legs from
>> the main pipe loop. Much more lossy but near instant hot water.
>
> Not worthwhile though for just two retired folk in a bungalow, as
> appealing as the idea is.
The other alternative is an under sink water heater of the flash boiler
> At the top of the picture can be seen the original loose insulation
> which is going to get rolls of 200mm insulation laid over. I think
> any electrics should as far as possible be over the insulation.
>
>> Hotels have a circulating loop for hot water with short drop legs from
>> the main pipe loop. Much more lossy but near instant hot water.
>
> Not worthwhile though for just two retired folk in a bungalow, as
> appealing as the idea is.
type. Tend to be electric which isn't ideal given energy prices now!
--
Regards,
Martin Brown
AnthonyL
Oct 30, 2022, 9:06:24 AM10/30/22
to
utility room. The original build was to have a system boiler in the
loft as you suggest. But the utility room has the main shower so
plenty of hot water very quickly delivered.
>Some makes also have a (not very) eco setting whereby
>it learns your usage patterns and keeps it internal
>heat exchanger hot.
>
smart neither is ECO always eco.
>Separate lagging might be a good idea if it is a
>combi and if your mains pressure is good enough even
>replacing a long run of hot 15mm pipe to the kitchen
>(with a tee junction for the bathroom) with 2
>separate 10mm hot water feeds to the kitchen and
>bathroom would reduce the delay.
>
which is well served. I'm not particular bothered about the delay
when filling the bath as it is only used a couple of times a year and
the wastage is only a small percentage of the usage.
AnthonyL
Oct 30, 2022, 9:18:41 AM10/30/22
to
On Sun, 30 Oct 2022 12:15:23 +0000, Martin Brown
>Your pipe run looks a bit close together to me and
>with old style wrap around lagging. Glass fibre? Wear a dust mask and
>gloves it is itchy as hell if you touch it and much worse to breathe!
>
Pretty sure it is felt, not irritating to touch. The insulation
underneath however is as are also the insulation rolls I've already
bought to spread over the loose insulation in the few feet up to the
eaves.
On that issue I've read that the insulation shouldn't go right to the
edge so as to allow ventilation. However as best I can see we have
soffits and facias (just been replaced with PVC) and there are no
gaps. We had half a dozen roof tiles replaced with vents as there
were signs of interstitial ventilation when we bought the house 6
years ago and that problem has gone.
>> I've had a closer look - see https://flic.kr/p/2nW3pYo
>>
>> Seems as if the delivery pipe is 1/2" (and earthed) and the return
>> pipe presumably 3/4" which I calcuate to be 5.7L. That's over a
>> gallon before any warmth comes through.
>>
>> As can be seen the pipes are close together but not touching, and
>> there are two spirals of felt wrapping. It cannot be cost effective
>> to try and replace the approx 15m length I can more or less readily
>> get to.
>>
>> Just trying to improve the loft insulation brings home how expensive
>> and time consuming the exercise is when not done as part of original
>> build.
>
>I'd say it was more tedious and unpleasant than anything else. If you
>can find it get the stuff that is wrapped in a thin foil on one side bag
>to minimise your contact even with the modern rockwool. Shiny side up.
I've already bought a few rolls of
https://www.wickes.co.uk/Knauf-Insulation-Super-Top-Up-200mm-Loft-Roll---5-61m%C2%B2/p/109451
It seems to have come pre-scored but also cuts nicely with a bread (or
ice - not sure) knife.
>>
>> At the top of the picture can be seen the original loose insulation
>> which is going to get rolls of 200mm insulation laid over. I think
>> any electrics should as far as possible be over the insulation.
>>
>>> Hotels have a circulating loop for hot water with short drop legs from
>>> the main pipe loop. Much more lossy but near instant hot water.
>>
>> Not worthwhile though for just two retired folk in a bungalow, as
>> appealing as the idea is.
>
>The other alternative is an under sink water heater of the flash boiler
>type. Tend to be electric which isn't ideal given energy prices now!
>
Yes that's been the dilema all along, use cheaper gas inefficently or
more expensive electricity, plus cost of install. Being well into my
70's I'll likely never see a ROI.
<'''newspam'''@nonad.co.uk> wrote:
>On 30/10/2022 10:33, AnthonyL wrote:
>> On Sun, 30 Oct 2022 09:38:06 +0000, Martin Brown
>> <'''newspam'''@nonad.co.uk> wrote:
>>
>>> On 30/10/2022 08:44, AnthonyL wrote:
>>>> The hot water takes a long time to come through to the kitchen and I
>>>> wonder if it is spending heat warming the cold water next to it.
>>>> Whilst I can see some advantage in effectively pre-heating if the
>>>> demand is for a lot of water, it would seem to be counter productive
>>>> if just a small amount of hot water is needed.
>>>
>>> No. That is just the distance the water has to flow before it fills the
>>> long pipe with hot water. There are some losses to the cold copper pipe
>>> it is in but losses to the adjacent pipe assuming it is not in direct
>>> contact with the hot pipe will be on the timescale of 10s of minutes.
>>
>> Not fully sure I understand "10s of minutes"
>
>That's about how long it takes for heat transfer through air from one
>pipe to the other.
Got it.
>On 30/10/2022 10:33, AnthonyL wrote:
>> On Sun, 30 Oct 2022 09:38:06 +0000, Martin Brown
>> <'''newspam'''@nonad.co.uk> wrote:
>>
>>> On 30/10/2022 08:44, AnthonyL wrote:
>>>> The hot water takes a long time to come through to the kitchen and I
>>>> wonder if it is spending heat warming the cold water next to it.
>>>> Whilst I can see some advantage in effectively pre-heating if the
>>>> demand is for a lot of water, it would seem to be counter productive
>>>> if just a small amount of hot water is needed.
>>>
>>> No. That is just the distance the water has to flow before it fills the
>>> long pipe with hot water. There are some losses to the cold copper pipe
>>> it is in but losses to the adjacent pipe assuming it is not in direct
>>> contact with the hot pipe will be on the timescale of 10s of minutes.
>>
>> Not fully sure I understand "10s of minutes"
>
>That's about how long it takes for heat transfer through air from one
>pipe to the other.
>Your pipe run looks a bit close together to me and
>with old style wrap around lagging. Glass fibre? Wear a dust mask and
>gloves it is itchy as hell if you touch it and much worse to breathe!
>
underneath however is as are also the insulation rolls I've already
bought to spread over the loose insulation in the few feet up to the
eaves.
On that issue I've read that the insulation shouldn't go right to the
edge so as to allow ventilation. However as best I can see we have
soffits and facias (just been replaced with PVC) and there are no
gaps. We had half a dozen roof tiles replaced with vents as there
were signs of interstitial ventilation when we bought the house 6
years ago and that problem has gone.
>> I've had a closer look - see https://flic.kr/p/2nW3pYo
>>
>> Seems as if the delivery pipe is 1/2" (and earthed) and the return
>> pipe presumably 3/4" which I calcuate to be 5.7L. That's over a
>> gallon before any warmth comes through.
>>
>> As can be seen the pipes are close together but not touching, and
>> there are two spirals of felt wrapping. It cannot be cost effective
>> to try and replace the approx 15m length I can more or less readily
>> get to.
>>
>> Just trying to improve the loft insulation brings home how expensive
>> and time consuming the exercise is when not done as part of original
>> build.
>
>I'd say it was more tedious and unpleasant than anything else. If you
>can find it get the stuff that is wrapped in a thin foil on one side bag
>to minimise your contact even with the modern rockwool. Shiny side up.
https://www.wickes.co.uk/Knauf-Insulation-Super-Top-Up-200mm-Loft-Roll---5-61m%C2%B2/p/109451
It seems to have come pre-scored but also cuts nicely with a bread (or
ice - not sure) knife.
>>
>> At the top of the picture can be seen the original loose insulation
>> which is going to get rolls of 200mm insulation laid over. I think
>> any electrics should as far as possible be over the insulation.
>>
>>> Hotels have a circulating loop for hot water with short drop legs from
>>> the main pipe loop. Much more lossy but near instant hot water.
>>
>> Not worthwhile though for just two retired folk in a bungalow, as
>> appealing as the idea is.
>
>The other alternative is an under sink water heater of the flash boiler
>type. Tend to be electric which isn't ideal given energy prices now!
>
more expensive electricity, plus cost of install. Being well into my
70's I'll likely never see a ROI.
Tricky Dicky
Oct 30, 2022, 10:13:46 AM10/30/22
to
preserve heat in the hot water pipe. If you are bothered about the hot pipe
heating the cold, separate them even a couple of centimetres will do and
some packers in between. Cover the lot with the loft insulation. The “hot”
pipe will only be hot whilst a tap is flowing the rest of the time it will
be cooling and eventually reach the same temp. As the cold pipe. I think
you are overthinking the situation too much and myself I would leave well
alone apart from covering both pipes with the loft insulation. As for the
pipe run and waiting a few minutes for hot water to reach the kitchen tap
there is little you can do as increasing the pipe diameter will not solve
the 20m run as it depends on the rate at which the boiler can heat the
water.
Richard
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