Green Building Forum - How much of a difference do better heating controls make?

How much of a difference do better heating controls make?

GarethC — Mon, 01 Feb 2016 10:28:20 +0000

I have TRV's on all my radiators, but I still spend a lot of time heating bits of the house no one's in at the time, because I can't be bothered wandering round the house turning them all off when I, for example, need to heat just my home office while working. And I'm always a bit suspect of always heating the hall where the thermostat is, regardless of what rooms we're actually using.

Gut feel is I could reduce usage by 20% or so if every room had controls which could individually call for heat without affecting others (and were preferably individually programmable). My current system does feel antiquated.

Has anyone seen studies of how much difference better controls make, or personal experience? Sorry if this has been covered already. Couldn't find a thread which covers it this way.

How much of a difference do better heating controls make?

gravelld — Mon, 01 Feb 2016 10:37:10 +0000

There are studies but I think they're often paid for by the control companies, and compare to no heating controls at all.

I think there is a convenience element that should be considered, as well as a satisfied feeling about wasting less.

How much of a difference do better heating controls make?

Simon Still — Mon, 01 Feb 2016 11:21:03 +0000

There's a return on investment/best use of time and resources question as well. The worse your insulation is the more difference you'll get from better heating controls (as you get less residual benefit from the heat you put in).

In our end of terrace victorian house we had no zoning bar TRV's. We had a gas fire in the living room and put the (wireless) timer/thermostat in there. That way in Winter we'd retreat to the living room in the evening and run the gas fire and the boiler would stop heating the rest of the house.

In that house putting heat into the living room in the morning did nothing for evening comfort and the same with the bedrooms. I think simple zoning to heat living rooms evening only, bedrooms morning only would have saved a decent amount.

Once you're very well insulated it has much less impact.

How much of a difference do better heating controls make?

SteamyTea — Mon, 01 Feb 2016 21:38:47 +0000

If you often work in just one room, then turn the heating off and get a fan heater.
I just heat where I am, easy for me as I live on my own.

How much of a difference do better heating controls make?

rhamdu — Tue, 02 Feb 2016 00:14:32 +0000

Posted By: GarethCAnd I'm always a bit suspect of always heating the hall where the thermostat is, regardless of what rooms we're actually using.

Then don't heat it. Room thermostats are only there for people who don't have, or don't understand, TRVs.
oh and a room stat is a convenient way of turning the whole system on or off.

How much of a difference do better heating controls make?

ringi — Tue, 02 Feb 2016 11:10:29 +0000

The hallway thermostat is there to turn off the boiler when there is no need for heat. Otherwise the boiler will spend all of its time cycling keep the water hot in the boiler bypass.

How much of a difference do better heating controls make?

barge17 — Tue, 02 Feb 2016 12:02:35 +0000

Cost benefit will depend on on whether you do your own plumbing. When we were down to 2 of us in our fairly big house, we fitted self - closers to the kitchen / livingroom doors. Then I installed a room stat/timer in the kitchen to trigger the boiler without any zone valve. The rest of the house continued on the original c/h motorized v/v which in turn was controlled by anoher digital stat/timer in the kitchen, set 1 degree C less that the other. The plumbing was fairly accessible and easy to alter.

So now if we want to heat the whole house, we simply turn off the kitchen stat: http://savewithcontrols.co.uk/products/horstmann-thermoplus-as1 which simply means pressing the big round button. Next day it always reverts to normal operation.

How much of a difference do better heating controls make?

gyrogear — Tue, 02 Feb 2016 12:13:55 +0000

Posted By: ringiThe hallway thermostat is there to turn off the boiler when there is no need for heat. Otherwise the boiler will spend all of its time cycling keep the water hot in the boiler bypass.

Could you not control this function with a timer, rather than a thermostat, so that the timer turns the circulator on at certain times when folks will be around, and then turns it off otherwise.

(I guess this depends on whether occupancy is time-related, such as kids in from school at 16:00, timer turns heat on at 15:47 etc.).

(This is how I intend to run my heat-pump DHW system, once I get authority from Mrs Gear...).

gg

How much of a difference do better heating controls make?

gravelld — Tue, 02 Feb 2016 12:53:54 +0000

Ideally you have them controlled by both - timer and thermostat. Or alternatively PIR detectors.

You don't really want a heating system running if it has already achieved target temp. That's a good few watts being drawn.

How much of a difference do better heating controls make?

ringi — Tue, 02 Feb 2016 13:04:06 +0000

I have never understood why it is not possible for a boiler to detect that all TRVs are closed based how how hard the pump is having to work.

How much of a difference do better heating controls make?

gravelld — Tue, 02 Feb 2016 14:18:08 +0000

Wouldn't that be quite variable? For starters there's the resistance of pipework, but also allowing for towel rails etc...

How much of a difference do better heating controls make?

joe90 — Tue, 02 Feb 2016 17:20:36 +0000

Posted By: ringiI have never understood why it is not possible for a boiler to detect that all TRVs are closed based how how hard the pump is having to work.

I think you will find that because of the bypass pipe work ( pipe across the flow and return) the boiler will turn itself off because the return water is too hot, therefore detecting that either the house is up to temp and/or all the trv,s are off.

How much of a difference do better heating controls make?

atomicbisf — Tue, 02 Feb 2016 20:23:04 +0000

Why not get a wireless thermostat/timer? We replaced our wired thermostat/timer in the hallway with a wireless one that usually lives in the living room. I opened up the TRVs fully on the radiators in the living room and dining room and set those elsewhere to a moderate level.

Seems to work much better than before as I'm not really interested in the hallway temperature.

Ed

How much of a difference do better heating controls make?

gravelld — Tue, 02 Feb 2016 20:29:51 +0000

Fine, if you've got a small house or one zone.

How much of a difference do better heating controls make?

ringi — Tue, 02 Feb 2016 23:50:22 +0000

Posted By: joe90I think you will find that because of the bypass pipe work ( pipe across the flow and return) the boiler will turn itself off because the return water is too hot, therefore detecting that either the house is up to temp and/or all the trv,s are off.

The boiler will then cycle ever few minutes reheating the water in the pipework to the bypass, the pump is also left running all the time.

How much of a difference do better heating controls make?

GarethC — Thu, 04 Feb 2016 17:51:19 +0000

Thanks all. Indeed I couldn't find decent evidence on actual savings. From estimates I did find, I think 15-20% feels realistic, and that's against a home with a situation like mine (TRVs + programmable thermostat) which is probably fairly typical?

Seems strange to me that few of the systems available provide as much controllability as you'd like though (per radiator remote control and programmability).

And those that (nearly) do seem a bit on the expensive side. Taking a typical Â£750 annual heating bill, 15% savings and my favoured 5 year return, I think Â£550 is about how much it's worth paying for such a system.

How much of a difference do better heating controls make?

gravelld — Thu, 04 Feb 2016 20:19:02 +0000

I think that, like those daft "save 30%on your bills by insulating your loft" messages the EST et al give out, such estimates are not that useful on an individual level.

Yeah, your estimate is a bit low given a smallish house.

How much of a difference do better heating controls make?

rhamdu — Thu, 04 Feb 2016 20:19:15 +0000

Posted By: ringiThe hallway thermostat is there to turn off the boiler when there is no need for heat. Otherwise the boiler will spend all of its time cycling keep the water hot in the boiler bypass.

That might work if the user decides when there is/is not a need for heat, and turns the room stat up or down accordingly. (Which is what we do with ours.)

I don't see how a device which senses temperature in one room can judge, by itself, whether heat might be needed in another room.

How much of a difference do better heating controls make?

ringi — Thu, 04 Feb 2016 22:44:35 +0000

Posted By: rhamduI don't see how a device which senses temperature in one room can judge, by itself, whether heat might be needed in another room.

It can't all the time, but we have the radiator in out hallway set so it take longer to heat the hallway then any other room. The hallway stat stops the boiler running when there is no possibility that any other room needs heat.

How much of a difference do better heating controls make?

Simon Still — Fri, 05 Feb 2016 09:23:26 +0000

Posted By: rhamdu

I don't see how a device which senses temperature in one room can judge, by itself, whether heat might be needed in another room.

Now that depends on the thermal performance of the house. You could make an even more valid claim about Weather Compensating controls - my Viessmann has ONLY an external thermometer and no input on the actual internal temperature.

In a well insulated house with a decent amount of thermal mass (say, a concrete floor with wet UFH) temperatures are very stable. I'm guessing the thermal mass provides a buffer which means short term impacts from cooking, sunlight or occupation have much less effect.

A single room stat in my house would be perfectly adequate (low temperature UFH, concrete slab on ground, timber with overlay system on upper floors)

How much of a difference do better heating controls make?

GarethC — Fri, 05 Feb 2016 09:47:55 +0000

How much electricity do the smart control systems consume? Anyone know?

How much of a difference do better heating controls make?

Mikel — Fri, 05 Feb 2016 10:56:42 +0000

Gareth,

I think the only sensible answer to your original question is: That depends!

We have had a GSHP installed in Mar 2013 and been in a trial of smart control systems for the past two years, starting Mar 2014.

We have been able to measure the CoP of the heat pump since Feb 2014

Feb 2014 CoP 3.2
Feb 2015 CoP 3.47
Jan 2016 CoP 3.49

The original system used just weather compensation and we have oversized radiators and not UFH. So for us it looks like the new smart controls have made about 10% improvement.

However, back to my "That depends". There are a load of qualifiers here.

How much of a difference do better heating controls make?

alec — Sat, 06 Feb 2016 20:22:01 +0000

How much of a difference do better heating controls make?

alec — Sat, 06 Feb 2016 20:24:37 +0000

Compensation controls wired back to the appliance make an incredible difference as they match heat generated to heat needed, and in all cases the resulting flow temperature can be just a few degrees above target room temperatures...

How much of a difference do better heating controls make?

alec — Sat, 06 Feb 2016 20:28:28 +0000

trvs and any thing that responds to higher than necessary temperatures must induce wastage..

How much of a difference do better heating controls make?

djh — Sat, 06 Feb 2016 21:30:55 +0000

Posted By: alectrvs and any thing that responds to higher than necessary temperatures must induce wastage..

That depends of course on what temperature the TRV is set to. Setting it so the user is comfortable presumably results in it being set at a lower temperature than the user is comfortable at, exactly because of the effect you allude to.

How much of a difference do better heating controls make?

alec — Sun, 07 Feb 2016 13:45:04 +0000

No, I am saying they only start shutting down when the room temperature is heading for over shoot..and most certainly they cannot tell the appliance to run at a lower temperature...

How much of a difference do better heating controls make?

gravelld — Sun, 07 Feb 2016 16:00:51 +0000

Depends on the TRV... The smart mechanical ones don't (ours don't anyway).

How much of a difference do better heating controls make?

alec — Sun, 07 Feb 2016 17:04:03 +0000

Yes Evohome with the OT bridge is the answer...

How much of a difference do better heating controls make?

rhamdu — Sun, 07 Feb 2016 17:39:09 +0000

Posted By: alecNo, I am saying they only start shutting down when the room temperature is heading for over shoot..and most certainly they cannot tell the appliance to run at a lower temperature...

That's assuming that comfort depends on a rock-steady temperature. Humans also have thermal mass, so we cope quite well with temperatures rising and falling over periods of 30-60 minutes. A slightly varying temperature may even be *more* comfortable than a steady temperature.