Posted by: @kev-m

They make an educated guess, but in theory they are a lot more educated in heat loss than you!  If they have done heat loss calcs can't you ask them what their assumptions were?  After all, you paid them.

Their assumptions are listed in the heat loss calcs. I gave an example above about how their assumptions for the glass is different.  It's the same for the wall, roof, etc in each room.  I just don't know who is right and who is wrong.

You should be able to measure how thick the walls are and tell whether they have a cavity, internal insulation or whatever.  U value of windows doesn't vary much, i.e. all uPVC double glazing is similar.  If it's recent conversion, can you get plans from your local authority planning portal ot even look at the building regs applicable at the time? 

The conversion was done in 2009 (not by us) and I have found very little in terms of plans or specs unfortunately.  All our windows and doors are oak framed and are double glazed.  Would you think 1.8 or 2.4 is a more accurate estimate of the U value?

We're having a new EPC done next week (need a new one for RHI, our last one is 8 years old), I will ask for their opinion too.

@novemberromeo,

You really need to know the sort of glass but have a look here:

1.8 is about the minimum available.

mcs is not designed to make sure anything but the paperwork is done properly. Getting the forms filled in correctly is no guarantee the system is designed correctly or is installed and set up properly. MCS just make sure the heat loss should be right, the radiators are correctly sized and the heat pump is big enough for the job. it has nothing to do with the pipework or how the unit is controlled. that is all down to the installer and system designer. 

@grahamh, that makes perfect sense. Thanks for explaining that. That means homeowners have to have full faith in the installer that what they're doing is bang on to deliver and design an efficient, fully functional system. Given the comments we see on this site and Twitter, installers miss the mark a lot, and that's very, very worrisome because fixing any significant issues with system design can be an expensive exercise. 

HIES have responded to my email, I feel their response is actually much more informative than the response I had from MCS:

First of all, I would suggest contacting MCS. The installer agrees to comply with their standards for Heat Pump installation and whilst there will be some areas that are open to interpretation there is a methodology that they should follow. MCS are best placed to say whether they have followed this methodology or not.

Secondly, the EPC should be ignored - they were not designed to do a detailed analysis, just a very high-level estimate to help house buyers compare properties.

We would need to see all the calculations to give a fuller answer. It's not possible to say who is right from the information provided, and it would require an on-site assessment in order to check the measurements and inputs anyway. The heat loss calculation result will differ depending on the inputs, which apart from the obvious (e.g. thermal efficiency of windows), can come down to smaller inputs such as how many times the door is opened every hour. We don't know all the inputs, or even the age and insulation status of the property, so we can only give an estimate. The reason that there is such a difference is because we don't know if the house is solid brick, cavity filled or built to the Building Regulations 2010. If we take the middle one of these then an estimate would be 11kW but if it's a relative new build it would be nearer to the 8kW that's closer.

Sorry there's not a black and white answer, hence why we suggest this is more of a question for MCS.

I hope this information helps with your choice.

It seems they would expect MCS to be able to help out, but as I've already found out, MCS are unwilling/unable to help.

In the meantime, I've decided to go with the 12kw pump and installation is booked for Friday 19th November.  I'll report back on how the install goes!

A couple of neighbours and friends have asked me how we've found getting a heat pump.  The answer: 'a nightmare! very stressful, you have no idea who to trust'. I hope things improve in the coming years if we're to have any chance of making this technology scale to the masses...

@novemberromeo, good luck with your installation and please keep us posted. Your installation date is just around the corner and we hope it all goes according to plan.

@novemberromeo, by the way we did discuss your dilemma in a recent interview (will hopefully be live in the next two weeks) and you settling on the 12kW was probably the right decision, by going down the middle. Hopefully it will be correct choice.

Tomorrow's the big day... installation!

Yesterday, our energy supplier (Neon Reef) went in to administration, so we've gone from a 13p/kWh fixed price tariff to a 25p tariff, almost doubling our costs. Great timing! Our fixed deal was due to last until March, so I was thinking we'd at least get a reasonably priced Winter before moving to the new-normal tariff.  Hey ho.

The kit has been delivered today,  ready for the installers tomorrow.  The LG box is HUGE! We've managed to stretch out our oil, we have around 100 litres left in the tank.  The last few days we've had the heating set to 25 degrees in every room to try and empty the tank as much as possible!

I'll post another update at the weekend...

Our ASHP is finally installed 🙂

Because our house already had underfloor heating in every room, I was expecting the installation to be a relatively simply job of removing the old boiler, connecting up the ASHP in its place, and installing the cylinder.  In my head I was expecting it to be 2 people for about a day.  Boy, was I surprised on Friday morning when 8 people turned up! 3 electricians, 3 plumbers and 2 apprentices (one of each) arrived like an army invading my home. 

Watching them operate was a beautiful thing - they worked so well together as a team, everything was efficient, well organised and they worked very, very hard.

Here's a pic of the old oil boiler, taken before they started:

And here's a pic taken in the afternoon - the old boiler has been removed and the ASHP put in its place.

Despite the best efforts of everyone, by Friday evening they had been unable to complete the job, but the plumbers promised to return on Saturday morning to finish it off.  Impressive to come back on a weekend, much appreciated.

By the end of Saturday, the ASHP was delivering DHW but not yet doing the heating.  Further electric work was required to finish it off, and the electricians came back on Monday morning.  By Monday afternoon, the job was complete and the ASHP delivering DHW and powering the underfloor heating.

Here's a photo showing the newly installed cylinder and control unit in our utility room:

It's been commissioned with the DHW set to 52 degrees and the heating temperature set to 40 degrees.  I'll see how it goes for the next week or so and start to look at optimising settings.

I'm awaiting the MCS installation certificate so that I can put my claim in for RHI.

@novemberromeo,

great news, be sure to let the forum know how it goes.  

Kev

@kev-m 

Thanks for the update Kev.

Using the model, I found that lowering the indoor temperature by 1C, could possibly reduce energy consumption by between 8% and 15%, dependent upon the ambient air temperature.

@kev-m 

Hi Kev,

Thanks for the data, very interesting.

What do you mean by 'a way of decreasing the sensitivity'?

One of the weaknesses with weather only compensation, is that it makes no allowance for other factors, and in particular does not respond to changes in indoor temperature. I feel that weather compensation with auto adaptation would provide a much more constant indoor temperature, and may slightly reduce energy consumption. It should also allow you to easily change the indoor temperature up or down, should you find that necessary.