Are room thermostats out of fashion?

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On Sun, 14 Dec 2003 00:47:43 +0000 (GMT), "Dave Liquorice"

Don't forget though that this part of the Building Regulations only apply when a new boiler is fitted either into an existing property or a new one.
My description of my own system was by way of illustration more than anything else.
My conclusion from looking through the Approved Document and the Good Practice Guide is that they are aimed at practitioners in the trade who are still installing conventional simple boilers and simple room stats because a) they understand them and b) they are cheap.
Therefore, given that that is the status quo, the point that struck me was that the authors are suggesting the marriage of the two as good practice because realistically that is what is often installed. They even refer to this as a minimum set of controls. With a simple boiler firing to full output or off and with simple bimetal thermostats, short cycle firing as a result of TRVs being virtually closed down is going to use some amount of energy which can easily be saved by hooking up a simple room stat.
However, even with a relatively simple modern condensing boiler is modulating to quite a low level and most that I have seen fire up at a level according to the amount of heat demand as referenced by the water temperatures. After all 3kW firing up for a minute once an hour is actually less than the pump uses.

My point was really that it strikes me that the Approved Document and Good Practice Guide make a point about the interlock thing because it can be easily achieved with what is often still installed today not that the authors are prescribing what *must* be done.
The legislation requires only that reasonable provision is made to save energy.
Once modulating and condensing boilers become the norm as it is suggested that will be the case within two years, the energy to be saved by interlocking the controls with a room stat is likely to be a lot less significant to the point where I suspect that using one will not make a whole lot of difference.
I am assuming here that time controls will indeed remain as they are which is to fully shut down the boiler and pump (notwithstanding overrun) when the heating period has finished.
Remember that with burner modulation the heat output goes down to a few kW to balance the heat loss so the residue of what we would be talking about would be on days when for *part* of the heating period boiler heat is required, but because of rising temperatures outside not for all of it. The number of days a year when that scenario happens in such a way that a very low burn rate of a few kW once or twice an hour is too much is very small. From an engineering standpoint at that stage it becomes very much a corner case to worry about switching everything off.
.andy
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Andy Hall wrote:

I think that is precisely the case.

Precisely.
The issue is 'conservation of heat and power'.
The modve away from single stat installations to TRV'ed installations is there to reduce unwanted heating of unused or little used rooms, and allow better control of house temperature. The gains are potentially considerable.
Keeping a single stat is a complete nonsense, excepat in the one case mentioned - some idiot who runs his heating in the summer. In which case one would likley set the stat above the level where it would ever come on in winter, to make sure the TRV'sd actually do their work.
The short bypass loop TRV solution is IMHO arguably better than no TRV's, and in practice no worse than a single stat would up - and indeed may be better, because if the single stat is wound up with no bypass, the bloody pump will stall.
I am not aware how the flow swiych thing actually works, because no one has explanied how the flow switch senses deamand when the pump is stopped. And if it simply cuts the boiler, not the pump as it were, then its no different from using the boiler internal stat.

Precsiely. In the same way that I was able to install single glazing in a new build, by demonstrating overall energy efficiency.
The spirit of the regulations is to avoid uncessary boiler firing, not uneccessary pump action. Addong a single stat doesn't do anythung ecept in the case where the whole house is already warmer than the heating could actually make it, and the bozo has left the heating on..

Yup. All I can say is that teh gains from 'single stat in the kitchen' to 'all TRV's and turn teh stat up to max' were significant for me. It wasn;t ideal, but it worked pretty well for a few years.
I couldn't even use a single stat on my fan heaters now, because they heating requirements for each room and the heat flow between then is far too complex. AND they don't shut the flow down, because the stats control the fans, not the flow, unlike TRV's.
One does the best one can with available technology.
Ideally one would have a stat in every room, and a zone valve, and some temp sensors outside...and build a bigger version of what my car has - they call it 'climate control - but as yet, no one makes such a control box.
The cost to me to install, to save a piddly 50 quid of oil a year, would be immense. Not least in terms of wioring, which would be equivalent to a complete new lighting installation in complexity. Better savings are assured by simply turning the whole heating system off when not required. when I need heat, I simply slap the system on, overriding the time clocks, and in summer its set to 'always off' and I simply punch it on when the odd cold day turns up.

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It requires the pump to turn to see if a TRV has opened up giving flow. A simplr timer can do this once every minute or so.
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Yes, but this requires the occupant to turn the heating off depending on the weather/time of year (and many people won't). Why bother requiring the user to do this, when a simple electronic device can do it for them. with proper controls, you can leave your heating on 365 days a year without energy wastage. Many people do.
In any case, I really don't see the problem with adding an interlock to a TRV based system. Just put a flow switch after the bypass/always on radiator and have it cut the boiler demand power. Set the pump to run for programmer CH on. Job done.

I would be surprised if the court (or building control department) decided that a reasonable provision is a system described in the approved document with an important feature missing. OK, a totally different system not directly comparable, but not a suggested system made less efficient. The approved document describes a suitable simple modification to an all TRV system that seems perfectly reasonable, reliable and easy to implement and prevents the wastage of energy.
Christian.
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On Mon, 15 Dec 2003 09:35:16 -0000, "Christian McArdle"

I certainly do that because it isn't necessary to turn it off. However it doesn't require a room stat to achieve that.

This was part of my point. During the heating season and during timed heating periods of the day, a modulating boiler will be supplying heat adequate to balance the heat losses from the building. The TRVs should be partly open around the set point and the boiler running continuously at a low modulating level or turning the burner off because it is producing heat at a greater rate than required. However there is still a demand for heat - just a small one. If a room stat were used in this situation, it would have to be set for a few degrees above this operating temperature or the boiler would not be able to meet the demand.
If you consider the electricity used to run the pump, it is around 80W or so. If a boiler modulating down to 3kW comes on for a minute an hour then that is less energy.
It's in the same league as a light bulb and how many people can say that they never leave lights switched on when not required.
If you also contrast all of this with a condensing boiler vs. not the energy saving is substantially greater,
My point was really that much better energy management can be achieved through the use of a modulating and preferably a condensing boiler. Given this scenario, adding a room stat is down in the noise in terms of being worthwhile.
Therefore, for it to be suggested that a room stat is mandatory is stretching the point from the legislative, economic and the ecological point of view.

In the case of conventional, full output on/off boilers, possibly. The focus is demonstrably on the wrong issues.

.andy
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Ah, but there is no requirement in approved doc Part L1 for a room stat, just a boiler interlock. It suggests in a non-exhaustive list that room stats and flow switches are appropriate for this use.
The addition of a flow switch interlock to an all TRV system would have absolutely no bad effect (beyond the small installation cost) and much good effect.
The pump would be running all the time, whether the flow switch was installed or not. The flow switch just causes the primary water to cool down if all the TRVs are hard off. If they are passing by at all, then the modulating boiler will be allowed to fire at the low rate. The flow switch doesn't force a modern low modulating burner to become cyclical.
The 80W from the motor can be saved by additional electronics to cause occasional pulsing every ten minutes or so, when the flow switch shows no flow (I see no requirement in Part L1 to do this, however). It would also be possible to incorporate the entire lot into a combi style boiler, although I doubt any manufacturers do.

Only if you assume that people actually turn off the system when it is warm outside. You can't make this assumption.
Christian.
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On Mon, 15 Dec 2003 10:38:25 -0000, "Christian McArdle"

Yes, but it's a recommendation, not a requirement.

Mine does exactly that, and modulates the pump.
That was my other main point. Since a modern boiler already has to have "intelligence" by way of a microprocessor to handle modulation etc. it is possible to sense all of the operating parameters and to control all of the devices like pump and motorised valves.

Not really. My point was that there are much more substantial savings that can be made by using modulating and condensing technology than can be saved by this corner case.
Part L1 also discusses having some low energy lights, but it can't make the householder use them.

.andy
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But most "building regulations" are recommendations. If you don't follow the recommendation, you have to prove your alternative is just as good.

In which case, the systems within the boiler provide sufficient interlock and the boiler is directly compliant with Approved Document L1 without further external controls.

However, it becomes much more than a corner case if you can't rely on the user to turn the system off during warm weather/over summer. Didn't someone suggest around 700W to keep a typical primary circuit warm? At 16 hours a day on the timer from May to October, that's around 2000kWh over summer, completely wasted. Over winter, the savings are much less, as the primary circuit will need to be warm for at least half the time, but savings are more likely to occur, as people will probably turn off the heating over summer, if they can work out the controls.

This part of L1 is totally ridiculous. I only use low energy bulbs, but refuse to install the ugly and expensive fittings that are mandated. A more reasonable solution to the low energy bulb fitting problem is to allow normal pendent fittings, but put a ten pound tax on each incandescent light bulb, to ensure they retail at considerably more than the cost of a proper bulb. The bulbs should also come with a health warning on the side, saying that you are causing irreparable and needless damage to the environment.
Christian.
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On Mon, 15 Dec 2003 11:41:58 -0000, "Christian McArdle"

Right, and all of this is easy for manufacturers to implement at low cost.

At 80 degrees possibly, but at 40?

I don't think that that would fly somehow. Until the appearance and colour temperature of these can be made to match tungsten lighting or at least be in the area, and be dimmable people, I don't think that they will become that popular.
I don't mind having fluorescent lamps in a workshop or even for outside lights but not for living areas. They are too cold.

.andy
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"Andy Hall" wrote |"Christian McArdle" wrote: | > ... put a ten pound tax on each incandescent light bulb, to ensure | > they retail at considerably more than the cost of a proper bulb. | > The bulbs should also come with a health warning on the side, | > saying that you are causing irreparable and needless damage to | > the environment. | I don't think that that would fly somehow. Until the appearance and | colour temperature of these can be made to match tungsten lighting | or at least be in the area, and be dimmable people, I don't think | that they will become that popular.
They'd become much more popular very quickly if incandescents cost a tenner each!
However, the price of CFLs is kept down because they are in competition with very cheap GLS. If GLS were taxed to be a tenner each then CFL manufacturers could creep their prices up and we'd all end up paying more to the manufacturers or the government either way.
Perhaps we should simply tax energy more; at full 17.5% VAT, and possibly with a tax on top of that for larger bills to go towards paying for new and greener power stations (because we're going to need new power stations 'real soon now'). At the moment large and inefficient users actually pay less per kWh because they get discounted rates.
Owain
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On Mon, 15 Dec 2003 14:11:37 -0000, "Owain"

It's counterintuitive of course. Utilities are already charged in this way in California.
Of course if light bulbs were heavily taxed, there would become a black market in them......
Perhaps the government would then introduce colour temperature detector vans.
Owain

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Tax them at source. Then people can ship in loads from France, except, of course, they are for 220V and will blow twice as often.
On the other hand, would people bother, particularly as the hassle of importing them illegally just isn't worth it, as the alternative is cheaper overall than what they're used to.

Another technological solution (easily bypassed, of course) to the silly fittings rule in Part L1, is to introduce a pendent fitting that only allows 25W to be drawn. Any more and it should flash the light. i.e. stick a 100W light bulb in and it has 1 second on and 3 seconds off. BTW, I'm not actually serious here, except maybe if I renting out a house and wanted to stop the tenant flogging the bulbs.
Christian.
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On Mon, 15 Dec 2003 15:53:59 -0000, "Christian McArdle"

That depends on the perceived need.
For example, in the past, tulip bulbs were imported at outrageous black market and legitimate prices, more recently ladies hosiery and nowadays it's tobacco and alcohol.
One doesn't *need* any of these but if the perception is there that these are luxury items then people will buy.

Do you have those pneumatic plunger time delay light switches? ;-)

.andy
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I never really understood those. You can get a DIN rail unit to do accurate hall light timing that can be connected up to any number of 99p non-latching switches. Instead, people install those pneumatic monstrosities (average service life: 2 months) at about 15-20 quid a piece.
Christian.
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On Mon, 15 Dec 2003 16:53:52 +0000, Christian McArdle wrote:

It's tradition. Also I suspect that it would take quite a bit of rearraging the wiring to convert the existing switching arrangements to using a timer.
1) There'll be 3+E between the switches but not between the MCB and the light fittings and on to the first switch. 2) Many older installations will probably not have a din rail unit but rather still use semi enclosed rewireables. 3) Commercially: The maintenance electrician will be called in to fix/replace a single duff air delay switch. He doesn't have the authority to spend the money to fix things better for the longer tmer.
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Christian McArdle wrote:

Well thats easy then. We wil eiher install 5 of them in paralllel, or simply buy some foreign ones in.

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Er, five in parallel would make them flash more. That would draw 500W, so the fitting would flash on for 1 second and off for 19.
It is easily bypassed, as in you could remove the fitting, or use side lamps. OTOH, if you had a particularly nasty BCO, such a fitting could prove useful. One trick, I suppose, if you are a builder, is to have your horrible fluorescent fittings and just remove them after the inspection until you get to the next house. Not that the BCO will care.
Christian.
P.S. I'm still not serious about this.
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On Mon, 15 Dec 2003 15:53:59 +0000, Christian McArdle wrote:

In most short hold rental flats the replacement of light bulbs would normally be the responsibility of the tenant. If the tenant left with the bulbs their cost would coem from the deposit.
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of
cheaper
allows
100W
to
Most don't pay the last month or twos rent and leave no deposit to be paid back, and generally owing rent.
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On Tue, 16 Dec 2003 10:07:21 +0000, IMM wrote:

This is simply not the case in my experience. Bad tenants do exist just like other kinds of bad people, they are a small minority especially where accomodation of any kind is at a premium.
Most tenancy agreements explicitly state that using the deposit to pay the last month's rent is forbidden and people abide by that agreement.
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