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[DamonHD]

IMHO (and the opinions of several plausible studies) insisting that comfort is all about very steady and uniform temperatures is overblown.  I spent some years living in a farmhouse partly heated with open fires for which neither is the case and yet many people see them as some sort of comfort ideal.

 

These things are partly a matter of (learned) personal preference, but overselling them will result in excess emissions and climate damage and ultimately will hurt us all.

 

Because I'm working around a problem with our shiny new heat pump install I have been trying several modes of operation and was probably not doing things optimally, but continuously on, even with a flow-temperature setback at night, felt stifling and oppressive and used *double* the electricity (kWh/d) of the intermittent (OpenTRV driven) call for heat that I am now back on.   Note: electricity in, not CoP or any other intermediate measure.  Intermittent, albeit in a house with reasonably good fabric, is *more* comfortable and much lower footprint and cost, in this instance at least.

[JamesPa]

2 hours ago, DamonHD said:

IMHO (and the opinions of several plausible studies) insisting that comfort is all about very steady and uniform temperatures is overblown.  I spent some years living in a farmhouse partly heated with open fires for which neither is the case and yet many people see them as some sort of comfort ideal.

 

These things are partly a matter of (learned) personal preference, but overselling them will result in excess emissions and climate damage and ultimately will hurt us all.

Clearly comfort is a matter of personal perception however the comfort benefits that were being discussed are the ones from low temperature operation(enabled essentially by weather compensation), not from continuous operation.  They are different both in perception and effect on consumption/cost. 

 

Low temperature operation causes fewer short term variations in temperature (timescale 1-3 hrs), because the output to the emitters is matched to loss, and reduced spatial gradients.  Many people will perceive this as more comfortable.  That's entirely different to varying the target temperature during the day/night to suit different use patterns (eg night time setback for better sleep).

 

Open fires in farmhouses are a rather special case, people do indeed like congregating near fires where the immediately surrounding air is heated to probably 25C plus, albeit that its possible to cool off by moving away.  However thats not a common arrangement in modern houses!

 

Incidentally low temperature operation is not just a feature of heat pumps, condensing boilers are (frequently) capable of it too and generally are more efficient if operated this way.  Unfortunately our largely clueless heating industry hasn't bothered to implement it unlike some EU countries where weather compensation has been mandatory since the early 2000s.

Edited December 30, 2024 by JamesPa

[JamesPa]

2 hours ago, DamonHD said:

Because I'm working around a problem with our shiny new heat pump install I have been trying several modes of operation and was probably not doing things optimally, but continuously on, even with a flow-temperature setback at night, felt stifling and oppressive and used *double* the electricity (kWh/d) of the intermittent (OpenTRV driven) call for heat that I am now back on. 

It sounds to me like your WC curve may be set too high.  If (a) you are stifling at night even with a setback, and (b) your TRVs are having any material effect during the day, then the most likely reason is that the flow temp is quite a lot higher than it needs to be.  Are you certain that you have adjusted the WC curve correctly (ie as low as it can go consistent with heating the house to the desired temp)? 

[DamonHD]

The WC curve is based on (1) Octopus heat loss calcs at design temperature at the low end and (2) my observation of best fit HDD base temperature over many years at the top end.  In other words I'm pretty much going by the book here.

 

I suspect that it *is* a bit too high but we haven't been anything like cold enough to calibrate (1) yet.  But in any case my own experiments (eg at Energy House) suggest that it is a silly waste of energy to heat unoccupied areas except in a very air tight modern (PH-ish) home where maintaining temperature differentials on purpose would be hard.  Eg ~60% waste heating bedrooms during the day in EH1 on a 'working family' occupancy pattern, ~15% whole house in my recent paper.

Edited December 30, 2024 by DamonHD

[JohnMo]

2 hours ago, DamonHD said:

felt stifling and oppressive

Reduce the overall temperature, steady heating allows cooler house temp, while still being comfortable.

 

Normally able to set temperature a good couple of degrees cooler. If your curve is correct radiator valves if installed shou6dtay fully open. Anything else means flow temp is set too high.

 

 

[JohnMo]

1 minute ago, DamonHD said:

(2) my observation of best fit HDD base temperature over many years at the top end. 

So if you have normally zoned to death, set way to high. Octopus heat loss calculation will most likely over egg the cake anyway. So possibly a mile out on curve.

 

4 minutes ago, DamonHD said:

Energy House) suggest that heating unoccupied areas except in a very air tight modern (PH-ish) home where maintaining temperature differentials on purpose would be hard is a silly waste of energy, eg 60% of all energy heating bedrooms as measured at EH1.

Not quite followed that do you have a link?

[DamonHD]

Note also that we have room temps set ranging from 17C up to ~20C for comfort, not too outlandishly 1C below CIBSE/etc norms.  Having those maintained with open circuits while sunshine and wind (and people) come and go is hard.  But we also (c/o OpenTRV) set back automatically when rooms are vacant.  No one WC setting is going to magic all of those!

[DamonHD]

@JohnMoI can't share the 60% figure as that wasn't published, but the second one is from https://www.mdpi.com/2071-1050/16/11/4710

[DamonHD]

I realise that I have now hijacked this thread.

 

Mods, if you wish to spilt off these posts into a new one, fine by me!

[marshian]

30 minutes ago, JamesPa said:

Clearly comfort is a matter of personal perception however the comfort benefits that were being discussed are the ones from low temperature operation(enabled essentially by weather compensation), not from continuous operation.  They are different both in perception and effect on consumption/cost.

 

Exactly - we are not talking about wasteful overheating of rooms (ie more than the heat loss of the room) but carefully matching the loss - now that may mean constant operation but at much lower flow temps

 

30 minutes ago, JamesPa said:

Low temperature operation causes fewer short term variations in temperature (timescale 1-3 hrs), because the output to the emitters is matched to loss, and reduced spatial gradients.  Many people will perceive this as more comfortable.  That's entirely different to varying the target temperature during the day/night to suit different use patterns (eg night time setback for better sleep).

 

I'm far more comfortable in a room constantly heated to 19 deg C than I am in a room which is heated to 21 deg when occupied and loses 5 deg overnight

 

The energy required to get the room back to temp is only slightly less than the energy required to keep it at a constant but lower target temp

 

30 minutes ago, JamesPa said:

Incidentally low temperature operation is not just a feature of heat pumps, condensing boilers are (frequently) capable of it too and generally are more efficient if operated this way.  Unfortunately our largely clueless heating industry hasn't bothered to implement it unlike some EU countries where weather compensation has been mandatory since the early 2000s.

 

Agreed - as stated elsewhere - condensing boilers were mandated but not the adoption of lower temp emitters which were essential to get the boiler efficiency improvements from the condensing mode they were designed to run in.

 

Effectively condensing boilers were installed and then run at the same flow temps as the old non condensing boilers - it doesn't get more stupid than that!!!

[marshian]

6 minutes ago, DamonHD said:

I realise that I have now hijacked this thread.

 

Mods, if you wish to spilt off these posts into a new one, fine by me!

 

I don't think a little thread jacking hurts - it was an old post resurrected anyway

 

PS I'm finding the discussion really interesting

[DamonHD]

Don't get me started on the condensing boiler issue: I took a cheap (~£1/home) solution to both Ofgem and Lord Callanan and neither were interested (or understood)...

 

https://www.earth.org.uk/OperationTuneup/

 

The https://moneysavingboilerchallenge.com/ thing showed it could be done!

 

 

Edited December 30, 2024 by DamonHD

[JamesPa]

1 hour ago, DamonHD said:

But in any case my own experiments (eg at Energy House) suggest that it is a silly waste of energy to heat unoccupied areas except in a very air tight modern (PH-ish) home where maintaining temperature differentials on purpose would be hard.  Eg ~60% waste heating bedrooms during the day in EH1 on a 'working family' occupancy pattern, ~15% whole house in my recent paper.

I suspect the truth is a bit more subtle.  If you don't heat a room at all it still gets fairly warm in most houses because of gain from adjacent rooms.   As a result the emitters in adjacent rooms have to emit more than they otherwise would, which means you have to raise the flow temperature thus reducing efficiency.  If instead you were to heat the room to somewhere around the temperature it gets to if you don't heat it at all, you will be able to drop the flow temperature.  The total loss from the house will be the same, but as its supplied at a lower ft the heat pump will require less input energy.

 

Ideally the heating of the unused room should still be low and slow, ie continuous drip feed not on off by trv.  Adjusting the lsv is the conventional way to do this but a trv that responds very slowly and never shuts off would be better.  I don't know if these exist yet or indeed whether opentrv does this.  Its obviously possible in principle and has the potential to simplify or completely automate radiator balancing.

 

1 hour ago, DamonHD said:

Don't get me started on the condensing boiler issue: I took a cheap (~£1/home) solution to both Ofgem and Lord Callanan and neither were interested (or understood)...

It was a good suggestion.  I suspect that, if they consulted the industry at all,  they would have received a negative reaction along the lines of "encouraging homeowners to adjust the controls on gas boilers is dangerous".  Of course the danger is that installers get more callouts, but so far as I can tell almost the entirity of design and installation practice both then and now puts this above all else.

[DamonHD]

38 minutes ago, JamesPa said:

I suspect the truth is a bit more subtle.  If you don't heat a room at all it still gets fairly warm in most houses because of gain from adjacent rooms.   As a result the emitters in adjacent rooms have to emit more than they otherwise would, which means you have to raise the flow temperature thus reducing efficiency.

Please read my paper: it explores exactly this.

 

https://www.mdpi.com/2071-1050/16/11/4710

 

Demanding overly tight temperature control WILL waste a lot of energy.

 

If running pure weather comp as I am the flow temperature is only determined by external temperature.

Edited December 30, 2024 by DamonHD

[marshian]

8 minutes ago, DamonHD said:

Please read my paper: it explores exactly this.

 

https://www.mdpi.com/2071-1050/16/11/4710

 

Demanding overly tight temperature control WILL waste a lot of energy.

 

If running pure weather comp as I am the flow temperature is only determined by external temperature.

 

I think you may miss a slight but subtle difference in the conversation

 

In my case I'm not trying to nail room temps to a 0.1 deg difference - I'm quite happy to accept a slight over or under over 24 hrs I'm not controlling room temps with TRV intervention - I'm only controlling the boiler flow temp to maintain the room temps in the target area.

 

As a result circuit size doesn't change - the TRV's remain fully open and I'm using all the 150 litres of water in the CH circuit acting as a nice buffer for heat distribution to the rads

 

If I was running the same process using an elevated flow temp and was reliant on TRV's to manage the room temps the circuit size could be anything from 2 rads to 13 rads. This is what I believe would be a wasteful approach in terms of energy because the boiler would cycle like a bitch in shoulder months as my heat loss is 4.7 kW at -2 and the min the boiler can get down to is 3.2 kW so at 10 deg C outside my heat loss is probably 2.2 kW

 

If my CH heat circuit was down to 2 rads the boiler would be cycling like crazy pissing energy out of the flue as the kW input would be massively over sized for the circuit volume.

[JamesPa]

1 hour ago, DamonHD said:

2 hours ago, JamesPa said:

I suspect the truth is a bit more subtle.  If you don't heat a room at all it still gets fairly warm in most houses because of gain from adjacent rooms.   As a result the emitters in adjacent rooms have to emit more than they otherwise would, which means you have to raise the flow temperature thus reducing efficiency.

Please read my paper: it explores exactly this.

 

https://www.mdpi.com/2071-1050/16/11/4710

 

Demanding overly tight temperature control WILL waste a lot of energy.

 

If running pure weather comp as I am the flow temperature is only determined by external temperature.

I will read your paper with interest but the summary you give above is absolutely no surprise to me.  I too am running on pure wc and find it very comfortable. I don't yet have the data to prove definitely its cost effective but have every reason to believe it is.

 

However I'm not sure how your summary above relates to my comment which is about how best to achieve desired temperature differentials between rooms while simultaneously minimising energy input, without any mention of tight temperature control.

Edited December 30, 2024 by JamesPa

[Roger440]

5 hours ago, JamesPa said:

 

 

It was a good suggestion.  I suspect that, if they consulted the industry at all,  they would have received a negative reaction along the lines of "encouraging homeowners to adjust the controls on gas boilers is dangerous".  Of course the danger is that installers get more callouts, but so far as I can tell almost the entirity of design and installation practice both then and now puts this above all else.

 

Surely one cant expect anything else? Installers are businesses. As soon as you have to "come back" your profit from the job starts evaporating. Its also, invariably, unplanned, so causes great disruption to your other work.

 

The 3 heating systems ive tinkered with are all fairly simple, but to get them to perform at optimum took many many hours of work spread over a long period of time. Commercially, that simply couldnt fly.

[Roger440]

On 28/12/2024 at 16:54, JamesPa said:

If my own house is anything like typical there is another advantage of operating low and slow, namely comfort.  I have moved progressively from a boiler at 70C to (the same) boiler at 50, to an ashp with weather compensation at 30-45.  Each gave a significant step change, for the better, in comfort.  The reduction in temperature gradients in both time and space makes a material difference.

 

The UK has been missed out on the advantages of low temperature, weather compensated heating for 20 years, other countries (in the EU) are more advanced.  How come we were so stupid?

 

Im not sure "we" are stupid. However, traditionally, people that go into the "trades" (like myself) are generally considered stupid and a failure by most of society. 

 

One cannot be overly surprised at the outcome of a system, that pushes those who are acedemically weak, into these trades.

[MikeSharp01]

6 hours ago, DamonHD said:

Please read my paper: it explores exactly this.

 

https://www.mdpi.com/2071-1050/16/11/4710

 

Demanding overly tight temperature control WILL waste a lot of energy.

 

If running pure weather comp as I am the flow temperature is only determined by external temperature.

Have read it, found it praiseworthy in its frankness and sense of surprise that what looks like Heat Geek's anecdotal view was found to be correct, and it answers many other questions while raising a few more in my mind. Firstly for our build which only has slab UFH keeping the bedroom temps down, what you describe as TRV clamping, cannot be done so may be a problem and although I have read loads here on this challenge. Meanwhike here at Millstone Manor we have TRVs on all the rads. Our boiler is now almost 10 years old and has no WC feature so runs on a single central stat. We have experimented this year with turning up the bedroom settings, lowering the flow temperature, to leave the boiler running for longer no full results yet but lowering the temp has had +ve impact.

[SteamyTea]

Just struck me that one of the problems of getting a heating system more efficient, and especially true of gas, is that the usage monitoring, and the energy usage when the outside temperature varies is non-existent.

It will be impossible for most people see a difference in usage.

Taking this winter, I have still not turned on my storage heaters, it really has not been cold enough.  Most days I have used less than 10 kWh.day^-1, and someday only 5 or 6 kWh (most of that will be DHW).

 

Globally, 2024 is on course to be the hottest year on record.

[JamesPa]

13 hours ago, Roger440 said:

 

Im not sure "we" are stupid. However, traditionally, people that go into the "trades" (like myself) are generally considered stupid and a failure by most of society. 

 

One cannot be overly surprised at the outcome of a system, that pushes those who are acedemically weak, into these trades.

For the avoidance of doubt and offence by 'we' I meant society, not the trade.  And your analysis about society's views is entirely fair IMHO.  Unfortunately we seem to value air-head celebrities more than people with brains who can actually get important things done.

 

14 hours ago, Roger440 said:

19 hours ago, JamesPa said:

Of course the danger is that installers get more callouts, but so far as I can tell almost the entirety of design and installation practice both then and now puts this above all else.

 

Surely one cant expect anything else? Installers are businesses. As soon as you have to "come back" your profit from the job starts evaporating. Its also, invariably, unplanned, so causes great disruption to your other work.

Thats also fair. 

 

It doesnt mean we should give up however.  What we should do is recognise that installers wont want to come back, and design systems/processes/simple instructions so they can avoid doing so without materially compromising performance.  Installers need to collaborate with this (because they are at the sharp end and have the fullest customer experience) for the good of their own reputation and society, but shouldnt necessarily be expected to lead it.     

Edited December 31, 2024 by JamesPa

[ProDave]

One thing never discussed in a "heat low and continuous" strategy is the ancillery items.

 

For instance, when my heating is on, I have four circulation pumps and 2 zone valves on.  At a rough estimate say 200W.  That is power not contributing to heating but used to push water around the system.  

 

I can't help feeling that is a significant proportion of the heating power a lot of the time so perhaps an argument for heating harder for a shorter time?

[joe90]

15 minutes ago, ProDave said:

perhaps an argument for heating harder for a shorter time?

Also we feel different temps at different times of day. During the day and being outside an indoor temp of say 18’ feels warm, however after tea and slumped in front of the TV 18’ could feel cool. (I know I do).

[DamonHD]

@ProDave I absolutely think that that is part of the deal.  I went back to check whether the circulation pump counts within the SCoP value or not, and have a relevant paper open, but have not convinced myself yet... If I only need 4kWh of heat pumping in a day but my circulation pump runs continuously at ~40W, I just severely dented overall real efficiency.  Exclusively chasing CoP, particularly a version that excludes these ancillary but significant items, and assuming that comfort can only be rock steady higher temperatures, may be a mistake.

 

(I take that 40W as ultimately adding to the space heat at a CoP of 1.)

Edited December 31, 2024 by DamonHD

[ProDave]

3 minutes ago, joe90 said:

Also we feel different temps at different times of day. During the day and being outside an indoor temp of say 18’ feels warm, however after tea and slumped in front of the TV 18’ could feel cool. (I know I do).

I proved that years ago working in an office at a constant 20 degrees.  Sometimes you were in shirt sleeves and loosening your tie as you felt too hot, other times you put your pullover on as you felt cold.

 

Same at home, we always feel warmer after a meal.