Hi Everyone.
I am new to the forum and a householder with a GSHP and know very little about the technical stuff.
I moved into this house in 2017 which is a hybrid barn and comes with a NIBE pump, water UFH and copious amounts of insulation. The bottom line is the house never cools below 21C which is way too hot to sleep with. Opening doors and windows all day will reduce the temp by a few degrees but as soon as they are closed it only takes 1 hour to be back to 21C. The pump is covered by NIBE service plan and has seen 3 visits out of routine and another 3 for breakdown. In 6 visits, each being a different technician, no one has been able to solve the problem and each saying that they have turned everything to a minimum. The current setting is for the house temp to be 16C with the option of using room stats which are currently all off. I have recently sent data info to NuHeat to analyse from pages 1 and 2 of the GSHP's information displays and they assure me that all is perfectly normal. The buffer tank is 22C and this shouldn't be contributing but if it is, can this be reduced further. Today the outside temp was 8C first thing this morning, the pump set to 16C for indoor temperature but alas every room is still 21C. Any thoughts or advice would be appreciated or even a plan to decommission and revert to the immersion for hot water. Many thanks, Julie

Thanks for your reply.
I don't quite understand your question but as I said I am only a householder and the buffer was mentioned by NuHeat.

We have a dedicated plant room in the basement which contains all the equipment tanks, pump etc., and is closed off from the living parts of the house by a fire door.
What appliances are you referring to as these could differ from one level to the next as the house is on 3 levels?

Many thanks,
Julie

Thank you for your comments. No one has mentioned diverter valves so this may warrant checking. The house is ridiculously over insulated (thanks to Sevenoaks BC) to the extent that we just cannot get the indoor temp below 15 whatever we try. We have window film on the SW and S facing windows as last summer the house was 35C in the bedrooms by 11pm. I have just found our old smart meter and will keep an eye on the electrical usage too.

What is the flow temperature going into the UFH pipes? Does the floor feel warm to walk on?

<blockquote><cite>Posted By: djh</cite>

You certainly shouldn't need to be running your GSHP (for space heating) at this time of year if your house settles at 15°C in winter </blockquote>

Agree - If the house is too hot with heating at minimum then turning off the heating could be a good option...

We have a IVT GSHP and this is how it's adjusted but the Nibe may well be different

There is

1. "temp increase/decrease"
2. "fine tune" which balances the weather compensation part of the system
3. "Room tempreture"

If it's set up like ours the "room tempreture" actually does nothing and it's run from the 1 and 2 and the room temp is disabled for maximum efficiency. What I am getting at is make sure 1. is turned right down

Hi Julie,

lot's of good points above, but maybe a bit tricky for you to try to unpick. The first step (as Jamesingram point to above) is...

- confirm if there is any active heating being done by the UFH. Don't try to understand if it's broken, just shut the heating side off completely, so there is no way any heat from the UFH (or rads if there are any) can be adding to the heat input to the house. The room stats are off I believe you said, but I would suggest closing the supply valve to the UFH and switching off the UFH circulation pump. Actually, if you have a standalone electric shower, it would be a more foolproof test to switch the heat pump off all together.

- leave it in that state for a few days, or maybe a week. At the end of that period either the house will not have cooled down, in which case you know there is NOT a problem with the UFH system; OR the house has cooled to say 18oC, in which case there must have been active UFH, but not in a controlled way.

When you've done that very rough test, please come back, and we can then try to help with the next step.

By the way, is the entire house too warm (ignoring the 35oC summer for the moment), or is it much warmer in different areas or different floor levels.

One crumb of comfort...99% of the people on here are jumping through hoops to make their homes warmer, not to diminish your problem of an uncomfortably warm house.

Thank you for all your comments and suggestions. The building is listed so no additions like external shutters or venting for air con I'm afraid, nor making changes to the roof elevations. Curtains were shut all summer on all elevations so that it's like we pretend the sun isn't shining at all and I am not a vampire! Not sure about whether there's heat recovery ventilation but there is some sort of system that runs in the basement that has a summer and winter setting.
The floors do not feel warm so I am assuming that the UFH is not coming on. I will try and upload the 2 pages of info that NuHeat asked for, which I believe answer the questions about flow rates etc. Most of the house is open flow apart from the rooms served by room stats. It would be nice, even in winter to come inside and not break into a sweat. I suppose this constant warmth is just something I particularly hate but would tolerate if we could settle at around 17C and add heat where and when needed. All floors are at 21C irrespective of appliances, windows (the basement doesn't have any) or furnishings and that is why I suspect something kicks in to maintain this constant level. Believe it or not, there are also 2 wood burners commissioned! All of your points are very valid and I can see that there are so many things that could apply. I shall contact NuHeat again who commissioned the installation in 2011 and see whether they can at cost, send someone (as suggested by djh) with sufficient knowledge to run some checks. If I start playing around with valves etc., I can see me getting the blame when something goes wrong. p.s. I shall follow up with some pics when I work out how to reduce their size and add more than 1 at a time. Thank you all again: I am indeed humbled by all your collective knowledge.

Posted By: hollyberryThe floors do not feel warm so I am assuming that the UFH is not coming on.

Assume nothing. Where the pipes go into the screed, are they warm?

>No matter how well insulated, all buildings will cool to ambient if there is no heat input into the building, thats just physics.

Is that actually the case for a very well insulated building? Doesn't solar gain add heat to the interior that may be lost only slowly? ie interior temp could be well above ambient outdoor temperature.

>Assume nothing. Where the pipes go into the screed, are they warm?
Possibly need an IR thermometer to check this - our UFH often works very close to target temperature so you certainly can't feel any warmth through the plastic pipe and often not through the metal

However, I find it really hard to believe the house is running at 21C without any input other than solar. Our house is can overheat in summer but in winter it does need some input from UFH to maintain 20-21C we run it at. We've switched off the heating to the bedrooms so they run very slightly cooler but only a degree or so. Very lightweight duvet's and just a sheet through most of summer is enough for bedding.

Would you be prepared to turn your electricity off at the tripswitch for a couple of days and see what happens?

Diagnosing the problem shouldn't be difficult and well within your capability even if you aren't a plumbing and heating engineer, but if you're not currently confident in your ability to do it we could start somewhere elementary and work up from there. Shutting off the electricity for a weekend (everyone can survive a power cut) will remove all but solar heat input to the house so we can see which way the temp goes. If you still need to run a fridge etc, perhaps an extension lead from the garage (which should be a separate circuit) to the house so you ca be sure that absolutely everything apart from the fridge is deactivated