Three Phase question

[JohnW2]

The majority of hot water heat loss is through the pipes, which is why they should all be insulated. They rarely are.

Indeed, but as you've said, even that does not usually constitute 'energy wastage' during the Winter.

Kind Regards, John

 

[ban-all-sheds]

Is warming the air in a floor/ceiling void which is thermally insulated from the rooms above/below not wasteful?

 

[JohnW2]

Is warming the air in a floor/ceiling void which is thermally insulated from the rooms above/below not wasteful?

It would be, but I said "usually" and the usual situation in a usual house does not involve insulation between floors, so a substantial proportion of heat lost from pipes provides useful heating (in Winter).

You appear to be back to nit-picking mode, something we had become used to living without. Some useful contributions relating to electrical matters would probably be welcome.

I have nothing more to say on this matter.

Kind Regards, John

 

[ban-all-sheds]

[EDIT]
PM to follow.
[/EDIT]

 

[John D v2.0]

It does constitute water wastage though, as there's no way of reheating the water in the pipes. But that's another topic!

 

[deadshort]

I have nothing more to say on this matter.

…….

 

[SimonH2]

Hot water cylinder heat losses are typically between 1 and 2 kWh per day for a modern insulated cylinder.
Some of the newest types can be less than 1 kWh. Older ones will be more, but unless it's an ancient totally uninsulated copper thing, the losses and the cost per year are usually insignificant.
Specified losses also assume it will be hot for the entire 24 hour period, and that the loss to the air is wasted - in reality the cylinder may not be heated all the time and in the winter any losses will contribute to the heating of the building.

And lets not forget the standing losses of a combi. Unless put in "be as annoying as possible" eco mode, these things fire up from time to time to keep the (DHW) heat exchanger hot.
Back at the end of 2010 I had the opportunity to measure the standing losses of two systems side by side. The thermal store I'd just put in the flat (in it's insulated cupboard) had standing losses of about 80W, the combi (BG badged Worcester Bosch) had standing losses equivalent to about 160W. That's about 2kWh for the cylinder, and 4kWh for the combi
In this case I can't claim that the losses from the cylinder went into space heating as the store is in the unheated garage under the flat (though it would be enough to keep any frost out). For the combi, I reckon a lot of the losses will be going up the flue every time the boiler fires up and flushes all the warm air out of the combustion chamber.

Is warming the air in a floor/ceiling void which is thermally insulated from the rooms above/below not wasteful?

Generally not - at least not to a significant degree.
Take, for example the space between ground floor ceiling and first floor floor. That space will already be warm from heat passing through the ceiling, and it will conduct heat through into the room above - previous comments about carpet and underlay being insulation have been noted. The space will reach some sort of thermal balance, having uninsulated hot pipes will slightly increase the temperature of this balance point.
Some of this heat will go to warming up the walls between ceiling and floor above. This wall will already be warm due to conduction down from the room above and up from the room below - if the extra heat from unlagged pipes makes the space warmer than the rooms above/below then some heat will be conducted up/down the walls into the rooms above/below. And yes, a small proportion of it will be lost through the walls - which is why we have rules/guidance on thermal performance of walls, cavity insulation, and so on.

Now, pipes in the void below the ground floor - losses here are wasted, and pipes really do need to be lagged.

 

[ban-all-sheds]

Sorry for my earlier, slightly intemperate, reply. I don't think the position I stated was wrong, but I could have stated it better.

 

[bernardgreen]

Running central heating pipes without insulation under a bath room floor is a form of under floor heating.

 

[JohnW2]

It does constitute water wastage though, as there's no way of reheating the water in the pipes. But that's another topic!

Whilst that's true, it's really only related to the length (and insulation) of the pipe runs, not the difference between stored and 'instantly-heated' hot water ....

... for example, I think that the length of the pipe path from my hot water cylinder to my kitchen tap (immediately below the tank) is probably similar to, maybe even less than, the length of the pipe path from my daughter's combi boiler (in her kitchen) to her bathroom (on opposite side of the house).

Kind Regards, John

 

[SimonH2]

Actually, in some stored water installations, there is a return fitted so that water can be circulated to ensure that hot taps are "instantly" hot. Various ways of controlling it, and in commercial installations (eg hotels) there are valves designed specifically for the end of line to control the flow.
Basically, a thermostatic valve goes at the end of each pipe run, and when the water is below some set point it allows through flow so the circulating pump can return it to the cylinder. There are various options, including ones that will re-open when above some particular temperature (or when electrically controlled to do so) and thus allow the system to be circulated at high temperature for legionnaires control.

 

[JohnW2]

Actually, in some stored water installations, there is a return fitted so that water can be circulated to ensure that hot taps are "instantly" hot. Various ways of controlling it, and in commercial installations (eg hotels) there are valves designed specifically for the end of line to control the flow.

I think that's pretty standard in hotels etc., and I presume it must be very wasteful of energy (at least, in Summer).

It's certainly not a new idea. In my present house, I inherited what appeared to be a largely Victorian plumbing system. Water heating was by a solid fuel boiler. When the boiler was running, there was a constant flow (by convection) of hot water through loops of (mainly ~2" iron) pipework - not just to ensure 'instant hot water' at more distant taps but the 'loops' also zig-zagged through a couple of 'walk-in' airing cupboards to keep them constantly heated.

Kind Regards, John

 

[Lectrician]

I think that's pretty standard in hotels etc., and I presume it must be very wasteful of energy (at least, in Summer).

It's certainly not a new idea. In my present house, I inherited what appeared to be a largely Victorian plumbing system. Water heating was by a solid fuel boiler. When the boiler was running, there was a constant flow (by convection) of hot water through loops of (mainly ~2" iron) pipework - not just to ensure 'instant hot water' at more distant taps but the 'loops' also zig-zagged through a couple of 'walk-in' airing cupboards to keep them constantly heated.

Kind Regards, John

Wasteful? It may waste a little energy (although in commercial installs, pipe lagging is far superior to domestic), but due to the lengths of pipe runs, the water saving is huge.

It is done this way in loads of commercial installs.

 

[JohnW2]

Wasteful? It may waste a little energy (although in commercial installs, pipe lagging is far superior to domestic), but due to the lengths of pipe runs, the water saving is huge.

True. If one's only concerns were financial, one would obviously have to do the sums, since water is probably fairly cheap in comparison with energy.

Kind Regards, John

 

[Lectrician]

True. If one's only concerns were financial, one would obviously have to do the sums, since water is probably fairly cheap in comparison with energy.

Kind Regards, John

I think someone has already done the maths, as for the last good few years, washing machines have not had a hot feed for this very reason.