Are room thermostats out of fashion?

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Hot air, more like. ;-)

.andy
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natural
cha
Astute observation Andy. When I pass people doing the cha cha cha the wind is fiercely hot. It makes their faces red and pushes their hair back. Totally ruins beehive hairdos.
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IMM wrote in message ... Obviously some people want to be me which is quite

Hmm. An old fart? LOL Capitol
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LOL
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wrote:

tenner
with
manufacturers
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'real
per
Good points Owain.

A year or so back, California had a power shortage. They blamed all sorts for it. Very few hit the real point. They were telling people not to use their washing machines, dishwashers and dryers, as these would create brownouts and then blackout. US appliances are hopelessly inefficient. If the US government committed to an EU like AAA rating, then none of this would have happened. CRT usage is dropping, collective heavy power usage, due to the introduction of LCDs, but the US government still is not legislating to reduce power.
Legislating is the only way. Do you think the building industry would have voluntarily built to the insulation levels we are to see in 2005? Not in a million years!!!! In 1990 when insulation levels rose by a miniscule amount, the British Building Industry said insulation was "cosmetic". Apart from the windows, nothing else of insulation you see.
In the UK all appliances sold should be at least AAA and insulation levels to Scandinavian levels - BY LAW.
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Christian McArdle wrote:

Ah, but that was averaged over the year. Its MUCH less in summer.
AND asummes long runs of pipework with full flow through them, and not insulated particularly well.
IF all TRV's are off, then the bypass loop will be the only thing getting heated. Basically thet is so small as to be almost irrelevant.
Anyway, the biggest savings in fuel are to be had by working from home.
Transport eats about 5 times what domestic heating does.
When I was commuting I was burning something like 70 liters a week in fuel. Times two for two people. That's 3500 liters a year to be saved.
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That depends on what your bypass is. A tiny bypass internal to the boiler is likely to be small. However, a permanent bypass through a bathroom radiator is likely to be much larger.
I'm still not sure why you are so resistant to having a ten quid flow switch in the system. Over the lifetime of the system, it will definitely save many times that in gas and isn't much of a risk.
Christian.
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Christian McArdle wrote:

So, you think people sit there dripping with sweat, with the boiler churning away, in teh summer? I don't think so.
Even the most stupid user can work out how to s3itch the boiler ON and OFF. FAR more than they can get the hang of adjusting 14 TRV's and a main thermostatt.

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Maybe not. But many will turn the heating on in October and off in May. For much of this time, no heating will be required.

Why bother, when a flow switch can turn the boiler on and off for them? There is no need to have room thermostats fighting with TRVs. A simple flow switch is fine.
Christian.
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With an overall stat, it won't come on...
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Dave Plowman snipped-for-privacy@argonet.co.uk London SW 12
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On Mon, 15 Dec 2003 14:36:04 +0000, The Natural Philosopher wrote:

You can't make the assumption in relation to the approved document. And yes, I do expect people to have the heating on during the summer, if they get too hot they open the window(s)...

My opinion of the great unwashed isn't that high.
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Dave Liquorice wrote:

Thank god the people who installed my boiler didn't expect it to be on all the time, as this thread seems to be saying is a Good Thing.
My bathroom would be roasting from the heat given off by the boiler being 'up to temp' constantly, from what I am gathering here. And that'd be with the rad off completely.
As it is, the bathroom rad is on only a fraction (not even half a turn!) solely to provide very low level heat to dry off my towel. The heating of the room is provided by the boiler itself, and if that ran constantly in winter, it'd be too hot, let alone if it was doing that in spring/summer!!
I *could* turn the heating off in summer, but I don't. The reason why? I have a programmable room stat. No TRV's, just the stat. In the summer the stat never calls for heat. Because it's set on the low side, I tend to notch it up a few degrees in winter per heating period, if I'm in, then I know it'll reset to a lower temp once I'm not there. This means it never fires in summer unless it's very unseasonable weather.
I *could* turn the boiler off in summer, but it supplies my HW. And it uses the heating circuit to cool down after doing so, which gives the system a gently waft through to stop the "I've just turned my heating on and it's not working" problem.
I see no point in keeping a boiler 'up to temp' all year round, it's lunacy. Unless it's exceptionally well insulated, it'll always leak heat into the surroundings - and there will always be some degree of heat travel away from the boiler in the metal pipework to the near surroundings too.
Just doesn't make sense on either a personal comfort level, or on an economical level either.
Velvet
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I don't think you understood the point being made or the technology involved
. Only older technology boilers heat up to the 80 or so degree temperatures during periods of low heat demand.
If your boiler is generating that much heat from the case, then it is presumably not a modulating or a condensing type.
If it were, then it would be modulating down to 40 degrees or so as the heat requirement becomes less. Under those conditions, very little energy is used warming the primary circuit water and typically the boiler, sensing the low rate of heat requirement won't fire anyway.
This has nothing to do with the case being insulated or even the pipework. The amount of heat generated is extremely low in any case.
Were you to have used a condensing boiler with even the fairly basic level of built in control, you would be enjoying gas bills approximately 25% lower and would not be experiencing the inappropriate heat from the appliance itself.
.andy
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Andy Hall wrote:

Quite possible I've not picked up on the types of boiler being talked about here. Mine's a non-modulating (though the one before it was indeed a modulating one). Don't have the foggiest if it's a condensing one - I doubt it (since they seem to be more expensive?).
FWIW, the old boiler (the modulating one) managed to heat the bathroom just as well. It's hard to say if this is actually from the case, or the fact that I have pipework running from the boiler down to the floor that 'you could hang fairy lights on, love' - it's not boxed in so there's a fair bit of heat radiating off those if the heating's on.
This thing about the boiler constantly staying warm/up to temp - are we talking about something that would apply to a system with a HW tank? I don't have one of those, and thinking about it I can see that perhaps it might make sense if there's a HW tank in the equation - though when thinking about that in the context of my other half's house, when the HW tank is warm (presumably it would be kept warm permanently by the boiler?) the airing cupboard *and* the rooms surrounding it are warm too, courtesy of unlagged pipes running under the floor from teh boiler to the airing cupboard.
I've been paying attention to this thread but it's rambled a lot and I really don't seem to have managed to gather the exact details of it all. I'd be grateful for anyone that could post a quick summary of the boiler and system layout this idea would and wouldn't be suitable for cos at some point I *will* own my own place, and chances are I *will* replace the boiler/CH/HW system in it :-)
Velvet
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Not in a correctly specced design. Part L1 suggests a suitable arrangement to heat a HWC is to have a separate pumped zone (the pump can be shared with other zones, if convenient) and a reasonably rapid recovery coil with cylinder thermostat. This means it can heat the entire tank in around twenty minutes. Provided suitable hysteresis and good insulation, the boiler can be kept from firing for quite some time before the temperature drops. Keeping the primary circuit from being hot most of the time reduces primary circuit losses, and promotes having a short high burn from the boiler, which is efficient.
Christian.
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Probably not. They are a bit more expensive (150 or so in a given model bracket) but the return on investment realises quite rapidly. An older type of boiler typically manages 65% seasonal efficiency, a newer conventional one around 78% (that's the minimum allowed now) and a condensing one around 91%. I replaced an oloder model with a condensing model and achieve 25-30% fuel savings.

During the heating season it reasonably should. Outside that, if the burner is modulating down properly the temperature should drop as low as 40 degrees except when recovering the hot water cylinder.

If you have a modulating boiler connected in this way, the way that it should work is that when the hot water cylinder requires heat, the motorised valve should move appropriately and the boiler to full power. The notion is that you want this job to happen quickly because a) you might want more hot water and b) in the winter you want the boiler to return to heating the house.
With a decent fast recovery cylinder, the recovery time should be a few minutes so in the summer the period that the boiler pipes are hot to 80 degrees quite short. One can always lag them as well In any case the hot water carrying pipes should be for some distance from the cylinder.. The cylinder in any case should be well insulated.

Let me try to summarise.
- The Building Regulations (the statutory instrument) require that reasonable provision is made to conserve energy when a heating system is fitted in a new house or a replacement in an existing one.
- The Approve Documents give guidance on how this *can* be achieved. They are not of themselves legally binding, but only recommendations - that is clear in the text.
- In other words you *can* do what is mentioned such as fitting a room thermostat to lock out the boiler, but it is not an absolute requirement. However, if you have a simple on/off 80 degree conventional boiler, this may well be an effective way to save some additional energy where TRVs are used. It is very unclear how much that would actually be because the room thermostat has to be set high enough to make sure that rooms with TRVs all get a heat supply for as long as is needed.
- If you fit a modulating, condensing boiler, apart from the inherent savings, it will tend to operate continuously at the required heat output rather than turning on and off. In the winter you want this and during the spring and autumn the power level simply drops as does the water temperature. In warmer weather, the heat required gets less and less and the boiler will respond to this by coming on at its lowest power level for ever shorter periods. In even warmer conditions this becomes very small indeed.
My point was therefore that the value of having a room thermostat just to lock out the boiler, becomes something that covers what is a corner case with this type of setup and the energy saved is down at or below the level that the pump is using.
Therefore to say that one needs to slavishly follow what it says in the Approved Documents is not true (because they don't require that) and some of the measures, like the room stat, become a lot less important with newer boiler technology because the equivalent effect, together with greater energy saving anyway can be achieved by using that newer technology. People seem to get confused by that and view the Approved Documents as being Gospel.
The Approved Document does allow for alternatives but proposes solutions assuming a minimum standard of boiler. My feeling is that this has been done because of the conservative nature of the heating and plumbing fitting industry, it was probably the maximum that the advisors to the legislators thought that they could get away with. Of course the other interested parties such as the controls industry would not have any objection either.
I think that it must also be realised that there is a political game here. The government has been pushing part L1, not for altruistic reasons but because it needs to be seen to doing something to meet the requirements of the Kyoto Protocol.
Having an engineering background, I tend to look at issues such as energy saving with a big picture view first and then to see which aspects are the most important in terms of return on investment, comfort, convenience etc. and to deal with those first, leaving other issues until later.
The government could have easily raised the barrier on boiler efficiency before now. Good quality condensing boilers have been in use elsewhere in Europe for 15 years at least, whereas the UK manufacturers did a very poor design, manufacture and marketing job with their first generation products, leading to a bad reputation in the trade.
This has paved the way for major German manufacturers such as Vaillant to enter the market themselves and by acquisition. The UK products have started to improve and there are smaller manufacturers such as Keston making excellent products at competitive prices.
The game is likely to change again in 2005. Current government thinking is to raise the seasonal efficiency barrier to 86%. This would essentially take conventional technology boilers off the market and mandate condensing products plus one or two other emerging technologies.
It would have been a much better move to have done this before and knock respectable sums from people's energy bills as well as reducing pollutant emissions rather than titting around with controls that make a lot less difference.

.andy
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writes

That depends on how much the house is insulated and draught free. You could fit an outside stat in a weatherproof box on the north wall. When above 15C (in your case) the heating is off. Then you have an interlock.
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On Sat, 13 Dec 2003 16:53:12 +0000 (GMT), "Dave Liquorice"

The legislation does not support that level of detail. That is not to say that implementing a room thermostat is not a good practice, but I can find nothing more than a recommendation suggesting that one is a good idea.
In my mind the question is, what constitutes a demand for heat? TRVs typically reduce the flow to radiators rather than closing it off completely unless the radiator is grossly over sized and the room temperature overshoots from it or a heat gain from another room or perhaps solar gain. Good temperature control in the rooms where TRVs are fitted would be achieved by their reducing the water flow to the radiators such that the heat output balances the heat loss at the required room temperature.
The heat output of the radiator in the location containing the room thermostat where one is used has to be reduced to ensure that the rooms equipped with TRVs have reached their set point.
Once that has been achieved, the boiler is turned off if a room thermostat is used with a simple boiler which delivers zero or full output only.
There are, of course, room thermostats with proportional control which turn the boiler on and off on a relatively short time constant to control the average heat output so that it is reduced as the set point is approached; and thus it is possible, even with a basic boiler to limit temperature overshoot which is said to be a significant energy waster.
As I understand it, though, there is an overhead in terms of efficiency for each on/off cycle of a simple boiler which does full power or off. Presumably, this is not substantial in comparison with energy saved by the overshoot not happening otherwise there would be no point.

I think that that may be taking too simplistic a view.
Given that the plumbing and heating industry is still very conservative and persists in installing non condensing non-modulating boilers, a room thermostat may well make an energy saving with it. I rather suspect though, that this has more to do with limiting the size of the temperature overshoot that can happen with oversized radiators and TRVs, than of whether there are short burns of the boiler.
One of the referenced good practice guides,
http://www.gas-news.co.uk/gpg302.pdf
discusses the fitting of room thermostats as part of an interlock scheme, yet mentions boiler energy management, modulating and condensing boilers only in passing, even though it is relatively recent. It seems to me that this is really an attempt to put a stick in the ground with the industry and to say that a room thermostat is part of good practice with a simple boiler.
However, modulating boilers, condensing or not are rapidly appearing, and even for the die-hard installer has some appeal because there is less commissioning to do.
It's also worth pointing out that it is quite easy for fairly sophisticated control capabilities to be built into the boiler as well. Most of this can be implemented in the firmware of the controller so from a manufacturing cost perspective is not a large additional factor. I suspect that the reason that more isn't done is because UK manufacturers have not had people with the skills to do the work.
For example, my own boiler has a very comprehensive set of controls and can have a number of additional sensors apart from those within the case.
On the input side, as a minimum it measures flow and return temperatures. On the output side, the microprocessor can control the burn rate from 3 to 25kW or off and the pump from 20-100%. Even with nothing else electrically connected, it will make a pretty good attempt at maximising its efficiency. If the heat demand is above the minimum 3kW then it will modulate the pump and burner anyway, so the issue of turning off altogether doesn't arise. In the range where some heat, but less than 3kW is required, it will come on for a short period, initially once per hour, measure the water temperatures and run until the heat demand reduces, then going off. The on period is remembered and adjusted so that the boiler is not coming on too much earlier or late than need be. I have seen the time between burns go out to as much as three hours with this hookup. During a normal day, it will have done a hot water cycle during this period anyway.
This is a fairly reasonable control system as it stands, but the manufacturer includes an outside temperature sensor anyway, which is placed on a north wall. It is then factored in as an input term to the controller, in effect providing a prediction based on the outside temperature. With this connected and operational, the control becomes rather better with an ability to adjust output before the house temperature changes.
Note that this is achieved with no room thermostat. From logs of burner operation, pump operation, water temperatures and internal house temperatures, the set points are achieved rapidly and without significant overshoot of inside temperature mainly through the modulating behaviour of the pump and burner.
I have added a room controller which is made by Siemens specifically for this boiler. Apart from time functions it has a temperature sensor for inside the house so that the boiler is presented with this information rather than just an on and off. The effect of adding this is mainly the convenience of a remote temperature control and even less temperature overshoot - now almost nothing. There is an installer setting whereby one can alter the relative sensitivity of this term and the outside temperature (loop gain controls if you like). In fact the defaults seem to work the best anyway.
So, I think that I could make a strong case to anybody who wanted to enquire that even without a room thermostat, I can achieve better energy use than a simple boiler with a simple thermostat because the minimum power output is very low and the boiler's built in algorithms do a pretty good job on their own.
The Approved Document and the referenced Good Practice Guide really only present *a* simple solution using a room thermostat for basic installations. Neither presents it as the *only* solution, and with increasing capability of boilers' own algorithms becoming increasingly part of mass market products, I suspect that these guidelines will need to be updated.
.andy
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[snip praise of technology way beyond the comprehension of most Plumbers!]
Andy, I didn't realise your MAN Micromat boiler was so clever. If only the UK industry would drag itself into the 21 century with some decent control technology. The cost of implementation is next to FA, a mid-range PIC or similar could do the job for a few quid. Even I could knock something together in a week or so's work, and I only dabble with PIC's and software occasionally. Mind, can you imagine your average Corgi optimising the PID parameters of the controller ;)
No thought not.
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Steve


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On Sat, 13 Dec 2003 22:24:27 +0000, Steven Briggs

The controller is manufactured by a Dutch company called Encon who appear to supply them to a number of German and Dutch condensing boiler manufacturers. I am not sure whether they also write the firmware but the copyright notices on the controller and the PC software to link to it has MAN Heiztechnik and Encon listed. You can monitor and log all of the inputs and outputs including the temperatures, pump rate, fan speed (relates to burn rate), motorised valve outputs and so on.
There are engineer's menus in the PC software for checking faults like ignition failures, running times, etc. and you can make changes within limits to some of the operating parameters than can't be reached from the front panel, but nothing that would compromise safety.

Exactly. I haven't looked in detail at the electronics but it is not sophisticated in terms of what's on the board.
The mechanical design is good in the sense that the major components like the pump, condensate drain, heat exchanger and internal pressure vessel plug onto the back panel and can easily be removed when necessary. Likewise the materials and build quality are of a very high standard and I suspect that that is where the main cost is.

.andy
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