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MCS heat loss calcs and Catch 22

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(@jswhite)
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188 kWhs
Joined: 2 years ago
Posts: 23
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I had a massively oversized ASHP forced on me because with the silly idea that the device should be big enough to heat the whole house. We have lived here for 26 years and never heat bedrooms, hallways and only the shower room on the coldest days and then for only an hour. I told them many times.
This was dismissed as irrelevant, I couldn't have a smaller heat pump, my right to chose had been removed by the MCS edict. About five different sources all trotted out a scripted justification 'What if you sell your house?' Shock horror, the new owner would have to chose their own heating, bathroom furniture and kitchen wallpaper etc.!
But no, the right to install a 16KW Samsung HP against my wishes was embedded in the MCS rules as though it was a statutory law. It is also a sleight of hand because previous oil boilers are often calculated to have enormous BTU sizes but they are not made to be incredibly inefficient when not used at capacity.
So I then had an oversized heat pump (the heat loss calculations suggested 12960KW total heat loss, so of course they fitted one 20% bigger). When used to heat the areas that I wanted to heat (two rooms) it burned through crazy amounts of money long before this years price rises came along.
The DHW was even worse, decorated with three pumps to waste electricity and a midnight raid to burn off legionalla (which is not necessary for domestic systems - it took ten minutes to look this up and find a report with this important detail). The fact is that 200 litre tank to supply one kitchen tap is a travesty.
I switched the whole device off at the mains last April and has not been used since. The benefit to the environment is that we have been pushed back into a medieval structure with no heating or hot water.
We have no choice but to replace th HP with a much smaller unit 4 or 5KW to heat two rooms with UFH and one radiator. No DHW.
I got the MCS spreadsheet for heat loss and found that my calculations produce a heat loss figure of 8500KW. The installer was persuaded to recalc the heat loss because they had not included a kitchen but subsumed that area into a living room. They had also mis-measured several rooms and included an outside workshop!. Then with all those changes rectified the re-done calculation came to 12,500KW - 465KW lower than the first one). I might be making a mistake in my calcs but they will not show me the assumptions or variables they used - isn't that a surprise?.
I complained the HIES - they said EPC was used to decide heat pump size. Wrong, Rude and pathetic.
I complained to NICEIC, they gave me two weeks home work to do providing lists, photos and emails etc, and then said it was not in their remit.
I asked HIES to give me access to the Ombudsman but they said they wouldn't because they didn't want to  'falsely raise my hopes' - condescending little..........
So we are facing a winter with either (i) an oil filled electric plug-in radiator for one room in the whole house. (ii) Selling up a house destroyed by this exercise (no kitchen because we removed ours to put a new UFH circuit in ready for the HP. We can't afford a new one if we have to pay for a different heat source. Or (iii) burning our way through three or four thousand pounds of electricity on an income of less than £17K to heat two rooms!.
And the much faunted RHI rebate came in at £29 every three months on condition that we pay £60 every three months for a fatuous maintanance contract. So that was cancelled.
What a mess.

Any advice would be greatly appreciated - John.


   
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(@kev-m)
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Joined: 3 years ago
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Hi John, firstly, sorry to hear of your problems. I won't get into the ins and outs of MCS other than I can see why they wouldn't give a grant for a system that heats part of a house.  Anyway, you are where you are.

First thing to say is that your 16kW Samsung ASHP will only actually be able to produce 12-13kW when you really need it so it's not as oversized as you might think. However, while it might be OK for your house, it's still going to be over sized for your 55m2 over 2/3 rooms. It might still be possible to run it reasonably efficiently and there are a few things you could do before replacing the ASHP with a smaller one. 

Modern ASHPs can modulate so can run at a lot less output than their maximum capacity.  Mine (Mitsubishi 14kW) will tick along at about 5kW at which point it's using a little over 1kW. That's less than a couple of oil filled rads. If the heat demand is any less, it cycles (switches off and on 2-3 times/hour).  That uses (and produces) even less energy.

I'm assuming your ASHP is set up properly with appropriate flow temperatures for your UFH

If you turn the target temp in your unused rooms down (not off) using TRVs or whatever other controls you have and set back the room temps in the rooms you do use at night, you might find it cheaper than using direct electric heating.  It's still going to be expensive because of electricity prices though.     

Your hot water.  An ASHP is still going to be the most efficient way of heating it with electricity. Apart from your kitchen sink, how do you heat your other hot water, e.g. baths/showers?  If electric it will be a lot more expensive than the ASHP. It doesn't take a huge amount of energy to keep a modern HW tank hot and you can change the legionella settings to once a week or fortnight.

Finally your RHI.  I'm not sure how it can be as little as £29 per quarter.  I get over £400 for a similar sized ASHP as yours. Do you perhaps have an additional heating system in your house?

I seriously doubt that removing your ASHP and replacing it with a smaller one that can only heat part of your house would be a wise move. What heating did you have before?

   

 


   
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(@jswhite)
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@kev-m Thank you for the time you have taken to reply in such detail. If it is possible to modulate this device in a way that would keep the costs down then I would take it. Is it a control panel setting or does it need an engineer to do that?
We had oil heating and miserable time with condensation in the tank or delivered in the tanker which froze and left us without heat for four weeks, in January. This is a rural area so getting qualified people is quite difficult. The oil tank was old so instead of spending on a replacement we went for the ashp.
The hot water problem is part of the cost. There are two pumps fitted to the device and an extra one was attached to one of the expansion vessels because the installer couldn't get it to respond properly. They might have low overheads in themselves but they are not providing anything useful. Our demand for hot water is one tap in the kitchen. The bathroom has an electric shower and we wash hands with cold water. No bath. An in-line electric element for the kitchen may well cost more to heat the water but there are no overheads when it is not in use. We pay for what we use, which is fine.
The plan is to heat as little as possible. The last two winters there has been three of us in the house but this next winter only two, my younger son and myself. He will be out all day so I will heat one room where I work but if the heat demand for that is so low we get into the wasteful situation of recycling of the hp then it will be a problem.
Any thoughts on this would be appreciated. Regards John


   
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(@kev-m)
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@jswhite 

The ASHP will use its software and inbuilt control systems to modulate automatically.  It 'knows' the flow, return and target temperature of the water in the circuit and should find the minimum power to maintain the target flow.  

 If the ASHP can't modulate down far enough it will 'cycle'.  That's not necessarily a bad thing as long as the frequency isn't too much.  3-4 times an hour is considered fine. 

I can't say if your Samsung and your system will work differently to this. There are a few threads on this forum about Samsung ASHPs if you search.

There will come a point where a single oil radiator is cheaper to run than your ASHP but I don't know where your situation is in relation to that point.   


   
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(@jswhite)
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Topic starter  

Hi Kev,

I afraid I have no faith in the control system on the hp. I tried many setting to lower flow, flow temperature, timing of heat demand and lower demand etc., When the fancy and much vaunted software was added (Homely) it took control away from me and the costs went up.
If this was a high performance car it would be known to cost a lot of fuel to reverse it out of the driveway, apart from leaving the engine off and pushing, it and this oversized heat pump are outside my ability to pay. It could be an art installation because it looks very nice but the engine is off.
This leaves me with the problem of dismantling the DHW system which should not have been fitted in the first place for a one tap house, and then having the whole system available to sell. I can buy a 4 or 5KW unit and have it fitted to already existing pipework. There are several posts on the site of people who have 5KW units heating houses similar to ours. I might still not be able to afford it but that will be my problem with income not badly a badly designed system foisted on my by applying abritary rules such as having to heat the whole house. (My own survey of people is that only one enthusiastically demanded that bedrooms had to be warm. The rest no. Cool bedrooms are better for sleep, its as simple as that). The 'whole house rule' is designed to benefit heat pump installation companies who can flog bigger units and get bigger grants, not the occupants of the house.


   
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(@batalto)
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@jswhite honestly I'm confused as to why you actually fitted a central heating system when you clearly don't want one. Central heating, by it's very definition is designed to heat a whole house. There is no system or scenario where what you want will be anywhere near as efficient. However what you want will be much cheaper due to the size you want to heat. Central heating will never work if you only want to heat one or two rooms. There is just way too much overhead and pipework. If you want to heat one room get an AC Air to Air unit. They are cheap and very efficient. Don't worry about the tank. Modern ones lose no heat anyway. Set it on a timer to heat in the middle of the day

12kW Midea ASHP - 8.4kw solar - 29kWh batteries
262m2 house in Hampshire
Current weather compensation: 47@-2 and 31@17
My current performance can be found - HERE
Heat pump calculator spreadsheet - HERE


   
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(@jswhite)
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Joined: 2 years ago
Posts: 23
Topic starter  

@batalto I've had oil central heating for nearly twenty years. The radiators in the rest of the house were useful if we had guests but it performed well heating the areas of the house where we spend most of our time, the living room/kitchen and when the boys were young, play room, now tv room.
The idea that an oil or gas central heating had to be switched on throughout the house would have been wasteful, so we didn't.
The lack of that choice with ASHP is so ridiculous that it is astonsihing that it is defended. As I said, I have asked numerous people if they heat their whole house and only one was emphatic that they wanted a warm bedrooms.
We don't think of ourselves as poor, there are many worse off, but we had nothing to spare for heating before the recent mayhem, and certainly no spare for rooms that we don't go in. The photo is a room that most houses have called a junk room but MCS consider that it is a bedroom, which means that is must be heated to 18C and a heat pump fitted that can accommodate a heat loss of 2000KWs a year. That is just under a quater of the heat loss that I calculated for the whole house (all rooms as per MCS instructions and using their spreadsheet) but when installers did it they conjured up a total of 12515 KWs per year to justify an enormous heat pump to go with it. It is a device we cannot afford to turn on. I took the photo a few minutes ago and it was my first time in that room for at least two weeks, during which time I was supposed to pay for heat that leaked out of the roof. Crazy.

image

"However what you want will be much cheaper due to the size you want to heat."
That is exactly what I want to hear. My choice, to heat the size of house within the building that I want to heat - a 4 or 5KW heat pump. The issue is how to dismantle this one and its useless DHW tank and fit one that is what we want. Any inconvenience that results from our choice is clearly our fault, I can live with that, but the inconvenience of being told to live by made-up rules that only benefit the installers is not going to happen.

 


   
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(@derek-m)
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Hi Everyone,

I have at last received a reply from my MP regarding the need for accurate heat loss calculations with regard to MCS requirements. I have posted below my original message and the corresponding reply. I'm afraid that it does not fill me with confidence.

 

Andrew,

 

During recent discussions on the Renewable Heating Hub, various issues have been raised concerning heat loss calculations, heat loss surveys carried out by installers, MCS requirements and Permitted Development.

 

Could you please ask Grant Shapps to explain why the flaws in the present MCS criteria, as detailed below, still exist, and what is being done to remove such disincentives?

 

The extract below is from a recent discussion.

 

What you describe is one of the major flaws in the present system, which is very much a catch 22 situation. To obtain the £5000 'bribe' one has to use an MCS accredited installer. Most installers now appear to charge £300 to £350 to carry out a heat loss survey, which may or may not be correct, and is very subjective. Consumers are advised to obtain several quotes, which could entail paying the best part of £1000, to have the same work performed several times, which I don't think would be the case if one is installing a gas or oil boiler.

As you have also stated it would appear that to be able to install a heat pump under permitted development, or particularly with planning permission, it is necessary to abide by the MCS criteria.

Unless I am missing something, there would appear to be little incentive for consumers to install heat pumps, since it would appear to be much cheaper and much easier to install a gas or oil boiler.

Did someone mention Net Zero? Were they joking?

Thank you in anticipation.

 

Derek.


   
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(@kev-m)
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Posted by: @derek-m

Hi Everyone,

I have at last received a reply from my MP regarding the need for accurate heat loss calculations with regard to MCS requirements. I have posted below my original message and the corresponding reply. I'm afraid that it does not fill me with confidence.

 

Andrew,

 

During recent discussions on the Renewable Heating Hub, various issues have been raised concerning heat loss calculations, heat loss surveys carried out by installers, MCS requirements and Permitted Development.

 

Could you please ask Grant Shapps to explain why the flaws in the present MCS criteria, as detailed below, still exist, and what is being done to remove such disincentives?

 

The extract below is from a recent discussion.

 

What you describe is one of the major flaws in the present system, which is very much a catch 22 situation. To obtain the £5000 'bribe' one has to use an MCS accredited installer. Most installers now appear to charge £300 to £350 to carry out a heat loss survey, which may or may not be correct, and is very subjective. Consumers are advised to obtain several quotes, which could entail paying the best part of £1000, to have the same work performed several times, which I don't think would be the case if one is installing a gas or oil boiler.

As you have also stated it would appear that to be able to install a heat pump under permitted development, or particularly with planning permission, it is necessary to abide by the MCS criteria.

Unless I am missing something, there would appear to be little incentive for consumers to install heat pumps, since it would appear to be much cheaper and much easier to install a gas or oil boiler.

Did someone mention Net Zero? Were they joking?

Thank you in anticipation.

 

Derek.

 

Very interesting and quite a detailed reply. And from a Lord no less.

I think the problem is that many/most suppliers insist on a full heat loss survey before providing any sort of quote rather than the two stage process described in the reply.  Because there is a shortage of suppliers they can get away with this.  There aren't many other domestic home services where you pay hundreds of pounds for a quote.    

IMO the majority of houses in the UK are not special cases and a good, experienced ASHP heating engineer should be able to look at a house, ask a few questions and give an adequate estimate of sizing cost that is good enough for an initial quote. Of course a more detailed survey is needed to confirm but even that could be made simpler by using standard models rather than a detailed bottom up approach that is full of often inaccurate assumptions anyway.        

If ASHPs are going to be the mass market solution for heating the industry needs to use mass market methods to deliver standard installations.  Think M&S rather than Saville Row.  Ford rather than Bentley.  Hungry Horse rather than Michelin stars.  The artisan/bespoke approach where everyone is different and the aim is a perfect solution won't work.  Good enough is good enough.   

Not sure if this has been posted before but some changes to MCR are planned.

https://mcscertified.com/mcs-scheme-redevelopment/?fbclid=IwAR1ae9dg_zqEDbHp6U3VeO02WEQekCMIDxYzzv7GAyVW03_FU7x90fIs8Q0

 

 

 


   
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(@kev-m)
Famed Member Moderator
5550 kWhs
Joined: 3 years ago
Posts: 1299
 

Posted by: @derek-m

Hi Everyone,

I have at last received a reply from my MP regarding the need for accurate heat loss calculations with regard to MCS requirements. I have posted below my original message and the corresponding reply. I'm afraid that it does not fill me with confidence.

 

Andrew,

 

During recent discussions on the Renewable Heating Hub, various issues have been raised concerning heat loss calculations, heat loss surveys carried out by installers, MCS requirements and Permitted Development.

 

Could you please ask Grant Shapps to explain why the flaws in the present MCS criteria, as detailed below, still exist, and what is being done to remove such disincentives?

 

The extract below is from a recent discussion.

 

What you describe is one of the major flaws in the present system, which is very much a catch 22 situation. To obtain the £5000 'bribe' one has to use an MCS accredited installer. Most installers now appear to charge £300 to £350 to carry out a heat loss survey, which may or may not be correct, and is very subjective. Consumers are advised to obtain several quotes, which could entail paying the best part of £1000, to have the same work performed several times, which I don't think would be the case if one is installing a gas or oil boiler.

As you have also stated it would appear that to be able to install a heat pump under permitted development, or particularly with planning permission, it is necessary to abide by the MCS criteria.

Unless I am missing something, there would appear to be little incentive for consumers to install heat pumps, since it would appear to be much cheaper and much easier to install a gas or oil boiler.

Did someone mention Net Zero? Were they joking?

Thank you in anticipation.

 

Derek.

 

Very interesting and quite a detailed reply. And from a Lord no less.

I think the problem is that many/most suppliers insist on a full heat loss survey before providing any sort of quote rather than the two stage process described in the reply.  Because there is a shortage of suppliers they can get away with this.  There aren't many other domestic home services where you pay hundreds of pounds for a quote.    

IMO the majority of houses in the UK are not special cases and a good, experienced ASHP heating engineer should be able to look at a house, ask a few questions and give an adequate estimate of sizing cost that is good enough for an initial quote. Of course a more detailed survey is needed to confirm but even that could be made simpler by using standard models rather than a detailed bottom up approach that is full of often inaccurate assumptions anyway.        

If ASHPs are going to be the mass market solution for heating the industry needs to use mass market methods to deliver standard installations.  Think M&S rather than Saville Row.  Ford rather than Bentley.  Hungry Horse rather than Michelin stars.  The artisan/bespoke approach where everyone is different and the aim is a perfect solution won't work.  Maybe good enough is good enough?   

Not sure if this has been posted before but some changes to MCS are planned.

https://mcscertified.com/mcs-scheme-redevelopment/?fbclid=IwAR1ae9dg_zqEDbHp6U3VeO02WEQekCMIDxYzzv7GAyVW03_FU7x90fIs8Q0

 

 

 

This post was modified 10 months ago by Kev M

   
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(@jamespa)
Noble Member Member
3891 kWhs
Joined: 12 months ago
Posts: 665
 

Interesting.  Many of the words in that response echo a response recently received by me from MCS when I wrote to them about the inadequacy of the current method for system sizing when applied to retrofits, particularly retrofits where fabric upgrades/extensions have been done at various times to various specifications.  I have asked MCS for permission to publish their response however they have refused.

I think the summary is:  MCS know that the current methods don't work in some/many cases and are considering alternatives but currently can't advise a timescale for implementation.

The ultra-cynical might re-state this as 'we know our product doesn't work in at least some cases, but we will continue to ship anyway (and inhibit MCS designers from inventing better ways to do it) because we haven't yet agreed on an alternative'.  

This post was modified 10 months ago by JamesPa

   
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(@jamespa)
Noble Member Member
3891 kWhs
Joined: 12 months ago
Posts: 665
 

Posted by: @jswhite

I had a massively oversized ASHP forced on me because with the silly idea that the device should be big enough to heat the whole house.

I feel for you.  My _whole_ house needs 7.5kW but the MCS brigade insist it needs 16kW.  I am fortunate that I spotted this before agreeing to an install. Currently as a result I am stymied and have no way to achieve an instal which is likely to work.   Unfortunately your installer will have followed the process mandated by MCS, so will be likely be fully protected.  

I have challenged MCS on the sizing methodology (in certain, important, circumstances) for retrofits, and received a response which I mention above.

You may wish to write to MCS about your experience.  The issue is not confined to cases where the householder objective does not require the whole house to be heated, it applies also to other scenarios where whole house heating is the design objective.

This post was modified 10 months ago by JamesPa

   
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