Posted by: @jamespa

↑

OK that's great.  3000l = 30MWh.  This corresponds, almost certainly, to a loss between 10kW and 15kW.

You need to be a bit careful when using past oil heating based estimates, because it is very likely you did not run the oil heating in the same way as you run a heat pump based system. You may recall a while ago we discussed the discrepancy between my oil heating based estimate, and my actual heat pump use based estimate, and came to the conclusion oil used less because it was only on part of the time, whereas a heat pump is generally on most or all of the time. Basically, the house ends up being warm most of the time, but you pay for that with increased energy use. Indeed, this is one of the heat pump negatives, because you can't do on/off heating (because they are too slow to recover from an off period), you have to run them most or all of the time, and this does cost more.   

Posted by: @tasos

↑

(a) The thermostat will work only if you exceed the desired temperature (in case WC does not work properly), to save you money.

(b) if you want independent control in each room, you have to install thermostatic valves. I don't know of any other way.

I cannot comment on your problem, since I don't have all the relevant data. It may be the pump is not sized properly or the piping is wrong or the room has too much loss. If the system is not correct, there is no way a thermostat will fix it since it just can't reach that temperature.

To answer:

(a) but I do have the WC set properly, see past posts of charts of my IAT, eg this one. There is simply no need for room stat interference:

(b) I don't want independent control in each room, never said I did, so no need to fix a problem that doesn't exist with devices (TRVs) that will almost certainly compromise performance. Ages ago, I looked at all of my TRVs, and said "Off with their heads!". They have remained decapitated ever since.

My problem (distant room a bit cooler than ideal) isn't your problem, you don't need to fix it, and I haven't asked you to do so. It's not a bad general principle that you don't 'fix' people/things, unless and until the person asks for a fix. As it happens I have already come to my own conclusions (pipework obstruction) and remedy (live with it), as previously posted.

Posted by: @pash44pump

↑

This now in answer to my request to provide input assumptions for the heat loss calculations

"In the scope document that Sandra shared with you, the details you are looking for can be found on pages 16–21 under the heading “Tecsurv Property Survey Form.” 

As noted, the majority of the ground floor of your property has existing underfloor heating. This has been recorded in both the existing and proposed emitter logs, which outline the heat requirements for each room based on their size and the construction of your home.

Additionally, on page 5 of the scope, you will find the room areas listed. This information enables Evergreen to accurately calculate the heat loss for each space, taking into account the building fabric.

All of the information provided has been used to complete the heat loss assessment for your home, and to size the heat pump appropriately"

This isn't good enough. I have now managed to render the docx document properly (sorry, had to do it online via what appeared to be a 'disposable' upload) and the 'Tecsurv survey appears to contain - one might even say be riddled with - errors and omissions.

EasyMCS, which produces the Evergreen software that Sustain Eco uses, are a get rich quick outfit. You pay them a subscription, and they give you the tools (including your very own consultant!) to do the job. EasyPeasyMCS. I don't see any requirement that a company that chooses to use them needs to have the slightest understanding of heat pump design and installation. Personally, modern idiom - 'document that X shared with you' - also gets up my nostrils, but that's by the bye.

You are on awkward ground here. I think you have a seriously botched design and installation. At the moment, that is just my opinion, and I can publish an opinion without fear of libel. If any one asks, it's called free speech. To take this further, you are going to have to prove to the best of your ability that it is a botched design and installation. The goons at MCS and the other bodies have been shown, not least bu accounts on this forum, to be both toothless and gutless. You are going to have to do this yourself.

Which all makes it seem rather daunting. But I think there is a valid shortcut. The bottom line is, if the design and installation are up to scratch, then the rooms will reach design temps on cold (design OAT) days. Full stop. Once the cold weather is upon us, set up the system for maximum output, see what room temps you get, and record them (a cheap temp data logger eg an RC-4 or three can do that for you). If some or all of the rooms fail to reach design temp, then invite Sustain to set things up so that they do reach design design temp. If they succeed, job done. If they fail, then you have clear evidence that the design and/or installation is not fit for purpose, and/or they are in breach of contract. No need to argue about heat loss calculation assumptions, survey deficiencies, or whatever, the proof is, so to speak, in the pudding. If the soufflé fails to rise, then the chef, and/or his equipment, is at fault.      

@cathoderay I hear you. I have just finished a letter to the company. I have asked for immediate rectification of the insulation issues due to Part L building regs deficiency, full details of the heat loss estimate assumptions and a meeting to discuss how to set up/adjust the system to meet design temperatures. I will update you on their response. Cheers

@pash44pump - good, you are on the case. Jaw jaw is always better that war war, unless and until jaw jaw has irrevocably failed. Good luck, and let us know how you get on. I, and I am sure others, will be very willing to help in any way we can, should you so wish.

@cathoderay thanks. I had a call within half an hour of sending my letter by email. My requests were

1) fix the insulation as per @transparent recommendations

2) send me the details of all heat loss calc assumptions

3) work with me to find a solution to why we don't hit desired room temps in winter

They have agreed most of 1) in that we have booked in a visit to remedy and they have accepted that current insulation is not acceptable. The plan is to replace with Rubaflex Class O Nitrile Pipe insulation. It is closed cell and smooth so that's a win. They are still wanting to use cable ties not tape as they state that is acceptable under MCS and that tape degrades whereas cable ties do not. They have promised not to do the cable ties too tight to avoid restriction. I feel that pushing back on that is difficult and I can always tape myself additionally afterwards (and may well box in). They have also agreed to cover all valves etc. They seem reluctant to run the pipes inside the Munson rings (not sure why) and I will push back on that. But mainly sorted and soon too.

They cannot send 2). The company they outsourced to no longer exists. It's clear from our discussions that they don't know how to do the calcs themselves. They claim to have done one yesterday in the office and it came out lower than the one in the scope document. They have though after some discussion, agreed to pay for an independent heat loss calc. They use a company called Regenertec and they have promised not to share the previous survey with Regenertec. They have also asked that I am present so that we can discuss variables, which is good, and they will share calcs and output in full. I will agree to having that done and want to make sure I am well prepared.

Regarding 3) they have also agreed to do that. There was some push back about the possibility that the ASHP is under-sized. They claim that the likely cause is the long pipe runs and the possibility that the assumption on insulation of UFH is erroneous (i.e. that house was not built to building regs spec as someone suggested they might). I think they genuinely believe that the ASHP is fit for purpose so let's find out. 

Thanks for all those that have helped so far. There will be more after lunch 😊 

@pash44pump 

It sounds like they may be a bit scared which is definitely to your advantage.  You have done a good job.

The only comment I would make is that, if you do invite them to set it up to heat sufficiently when it's cold (as @cathoderay very sensibly suggests) they may well just whack up the flow temp to max and disable WC.  This will cost you a fortune downstream so beware of letting them off the hook in this way, some caveats needed I feel.

@jamespa noted. Thank you

Lunch over. Back to it

Some more observations from discussion with installer. Given they raised possibility that the UFH is not insulated properly (as a question) - is there any way I can check this? Difficult when the pipes are buried in screed. I don't have building regs documents for the 2006 house build. Can I get them from somewhere?

We are probably not going to run any tests until the ASHP-sized elephant is dealt with via the new heat loss calculation but I'm wondering where you suggest I start to see what the system is currently doing (albeit in nice weather).

One thing the installer mentioned which raised alarm bells with me was that there is an immersion within the buffer tank, which is not wired in. He was suggesting that they could wire that in and we could boost the temperature at the coldest times of year. Sort of sounds like we could increase our UFH flow temps by getting a funnel and boiling the kettle a few times and pouring it in or am I missing something apart from a red flag that they really do think the pump is not big enough.

On that question, did I pick up something that my Midea 12Kw can be uprated via a dip switch. Does that literally mean that is has more potential power under the hood or have I misunderstood something? I think @cathoderay you raised that somewhere.

Look forward to your thoughts

Various comments now all collected together in one post:

Posted by: @pash44pump

↑

They cannot send 2). The company they outsourced to no longer exists. It's clear from our discussions that they don't know how to do the calcs themselves. They claim to have done one yesterday in the office and it came out lower than the one in the scope document. They have though after some discussion, agreed to pay for an independent heat loss calc. They use a company called Regenertec and they have promised not to share the previous survey with Regenertec. They have also asked that I am present so that we can discuss variables, which is good, and they will share calcs and output in full. I will agree to having that done and want to make sure I am well prepared.

First things first - you have got a positive result - what looks like a workable plan for this. But having said that, there is still a huge question: how on earth can it make sense to have a firm install an ASHP system when they don't even understand the basics of design? Why isn't MCS saying, no, no, no, you cannot do this? We all know the answer to that question.     

Posted by: @pash44pump

↑

Regarding 3) they have also agreed to do that. There was some push back about the possibility that the ASHP is under-sized. They claim that the likely cause is the long pipe runs and the possibility that the assumption on insulation of UFH is erroneous (i.e. that house was not built to building regs spec as someone suggested they might). I think they genuinely believe that the ASHP is fit for purpose so let's find out. 

Again, in the round, this is a positive development - they are prepared to work with you. But, again, I have to say, they and/or their sub-contractors designed the system, and so knew all about, for example, the long pipe runs, and thus had the opportunity to either design differently, or do something else to relieve the problem (if it is the main problem, I still think substantial under-sizing of the heat pump is the primary problem). As you say, time, or rather the cold weather, will tell. 

Posted by: @pash44pump

↑

I don't have building regs documents for the 2006 house build. Can I get them from somewhere?

@transparent will know if anyone does.

Posted by: @pash44pump

↑

I'm wondering where you suggest I start to see what the system is currently doing (albeit in nice weather).

No harm in making observations now, but I think in reality you have go to wait for the acid test, what it does in cold weather. That, and that alone, will give you the definitive answer.

Posted by: @pash44pump

↑

One thing the installer mentioned which raised alarm bells with me was that there is an immersion within the buffer tank, which is not wired in. He was suggesting that they could wire that in and we could boost the temperature at the coldest times of year. Sort of sounds like we could increase our UFH flow temps by getting a funnel and boiling the kettle a few times and pouring it in or am I missing something apart from a red flag that they really do think the pump is not big enough.

I like the kettle analogy and the answer is no, no, no! In any event, ideally you will deep six the buffer tank before too long. The general design principle (and indeed MCS requirement until recently) is that the heat pump must be able to supply 100% of the heat loss at design conditions. Above and beyond that, individuals can, if they so wish, choose to add supplementary heating. There are exceptions, hybrid systems, but in most cases they make no sense. Furthermore, running an immersion heater to boost the heating in cold weather will cost an arm and a leg, whenever it is in use.

Posted by: @pash44pump

↑

On that question, did I pick up something that my Midea 12Kw can be uprated via a dip switch. Does that literally mean that is has more potential power under the hood or have I misunderstood something? I think @cathoderay you raised that somewhere.

My understanding, based on something GH (one upon a time Mr Freedom Heat Pumps himself) once said, plus my own supplementary observations eg dimensions, weights, the way the manuals are put together and indeed what the manuals actually say) is that the 12, 14 and 16kW all have the same hardware, the output is set in software using the dip switches. At least that used to be the case, I have since heard a rumour that they have removed that capability, since folks were buying 12kW units at 12kW prices, and the switching them to 16kW. Your unit will I suspect predate that change. The dip switches are accessible on one of the PCBs in the unit, and you may even have a sticker on the inside of a panel telling you what the settings are, if not they are in one of the manuals. Note that as I suggested before, I think any such change, if done, needs to be done by your installer, (a) to ensure the responsibility lies with them and (b) not to hand them a 'client messed with the system' get out of jail clause. 

Posted by: @pash44pump

↑

He was suggesting that they could wire that in and we could boost the temperature at the coldest times of year. Sort of sounds like we could increase our UFH flow temps by getting a funnel and boiling the kettle a few times and pouring it in or am I missing something apart from a red flag that they really do think the pump is not big enough 

It's a known technique and heat pump manufacturers even sell 'backup heaters'. There is a reasonable engineering argument for it to deal with extremes, but not to deal with an undersized pump if that's what it turns out to  be (and to do it this way risks violating the bus rules).  A near neighbour of mine deliberately had his system designed with a backup heater to avoid a double fan ashp.

However it sounds like B1 is so far out that this would be deployed rather too much of the time to be sensible.  I wouldn't entirely rule it out but I would definitely regard it as a last resort and acceptable if it's only needed for a few days per year (say 5 or less).

Posted by: @pash44pump

↑

We are probably not going to run any tests until the ASHP-sized elephant is dealt with via the new heat loss calculation but I'm wondering where you suggest I start to see what the system is currently doing (albeit in nice weather).

I'm not absolutely sure that the new heat loss survey will put it to bed, it is , after all, just another estimate albeit one you have more control over and can influence more. It may, it may not.  I would probably still have it done (although there is a bit of a risk it's a tool to prove you have a large enough pump) but in the end the proof of the pudding is in the eating.

I think once you need the ashp for heating reasonably seriously you can start taking measurements, recording the conditions. You can always turn up the flow temp temporarily to simulate certain conditions.  Determining temp drop from place to place and how the controls work would be a good starting point as these aren't going to change if the ashp is uprated and there is very high probability indeed that they are a part of the problem.  You are unlikely to be able to finalise until it gets really cold though.

Posted by: @pash44pump

↑

Given they raised possibility that the UFH is not insulated properly (as a question) - is there any way I can check this

I can't see how you can do this without digging.  However if you happen know what the mixing valves were set to when it was run on oil you might be able to infer something.

Posted by: @pash44pump

↑

Posted by: @pash44pump

↑

I don't have building regs documents for the 2006 house build. Can I get them from somewhere?

@transparent will know if anyone does.

All previous releases are archived on the Planning Portal.

Here's the link for Part-L and its historical amendments.

I think everyone reading this should download a copy of Part-A (Structural) from 1992.

That was the last edition in which Appendix-A was included.
It's the look-up tables for timber spans capable of supporting particular loads.
That's how you know the size of timbers required for floor-joists and rafters etc.

The later versions of Part-A omit Appendix-A because they wish you to buy a copy rather than read the free derivative online.

The tables are still valid however, because they're based on core physics.
AFAIK gravity hasn't changed from 9.8m/s^2 for the past few millennia.