Posted by: @ashptenant

↑

Hello, I am a tenant in a very recently refurbished house which, as part of it's complete gutting and refurb, had an ASHP installed last year. We are finding it hideously inefficient and the bills are terrifying! £550 for last month alone. Completely untenable for us.

During the very cold frosty weather recently, we were barely getting up to 13 degrees in the house most days, though the water was always really hot. This was despite running the system 24/7. The house is very well insulated, with thick, new, loft and cavity wall insulation, as well as new double glazed windows throughout.

Our landlord has been trying to help sort it out, but has apparently been getting completely contradictory advice from the various engineers he's spoken to, plus the rep for the system. It's an LG.

The landlord discovered that the two handbooks provided with the system differ also, with the install schema showing the hot water and heating pipes either side of a valve connected one way, but the other booklet describing them connected the other way! He hasn't been able to get a straight answer regarding which is correct from anyone; some engineers say one way is correct, others at the same company say it's the opposite!!!

Can anyone advise please?! 

Can you provide a photo of the valve in question.

How large is the property? What type of heat emitters (radiators or UFH) is installed? Is there a buffer tank or low loss header installed? Is the system operating in weather compensation mode?

 How many kWh's of electricity are being used?

@derek-m thank you for your reply. I don't know the answers to lots of those questions but will do my best with those I do know.

It is a fairly modest three (small) bedroom house. We have radiators which were new last year, installed with the heating and are slightly larger style boxy radiators.

Photos of the set up below. The metal box you can see hanging was the electrically controlled valve switch, which had been attached where I am pointing in the other image. The landlord has disabled this valve and since then the heating has finally been  achieving temperatures of about 19 degrees. The water is less hot and we have less of it, which I presume is the off-set of having warm radiators.

My landlord (who is also a builder) has temporarily disabled the valve to leave it permanently open over the Christmas period, after which he hopes to get a straight answer from someone as to which way the pipes should be fitted. On noticing the discrepancy between the two install instruction booklets, he wondered if the pipes were supplied connected upside down - this would be the case according to one of the instruction books. One tech person he spoke to said they were the wrong way up, but another said they weren't!

The disconnected valve is currently hanging loose as you can see in the images. It - or something in the boiler cupboard! - ticks loudly every time the heating is on since it was disconnected. We're not sure what this means. We informed the landlord who conjectured it's the immersion heater making the noise. 

Before he disconnected the valve box and left it manually set open like this, the pipe which goes to the hot water tank was frequently too hot to touch, (water is set to 50oC) whilst both the pipe serving the heating and the radiators themselves were at best lukewarm. The landlord was told by someone in the technical department at LG that the system is plumbed to prioritise hot water with heating being what's left over. This seems a bit odd, especially given that at minus 5 temperatures, the heating couldn't even heat the house above 13 degrees, even on 24 hours a day.

We have been having to boost with electric fan heaters. This, plus the fact that everything in our house runs on electric and we do not have a smart meter, means I can't give you an accurate kwh usage figure I'm afraid.    

How could I check if it was operating in weather compensation? Should it be? Please excuse my ignorance, I'm not even sure what that is. Aside from adjusting the wall thermostats and the water temperature on the main in-cupboard thermostat, we haven't tinkered with the set-up at all. 

Thanks for the photos.

The controller is normally set to give priority to producing hot water, but this can often be changed by a setting within the controller.

If you look closely at the valve, you will see that the three pipe connections are labelled 'A', 'B' and 'AB'. The warm water from your heat pump should be connected to port 'AB', port 'A' could be connected to the hot water cylinder and port 'B' to your radiators.

It is difficult to tell just looking at photo's, but I suspect that port 'A' is connected to your hot water cylinder, but port 'AB' is actually connected to your radiators, and port 'B' is actually connected to the warm water from your heat pump, via a buffer tank which is located in the bottom section of your hot water cylinder. Your system would therefore appear to be incorrectly piped up.

Can you post a photo of the manufacturer's label which will be somewhere on the side of your hot water cylinder. Also do you have details of the the size and model of heat pump installed.

@derek-m very many thanks indeed for your help and for sharing your understanding and expertise. It is so much appreciated! 

Having checked the pipes (pic attached) I find that port AB goes straight through the outer wall. Port A is the one which goes up and into the tank, but also diverts into all those various other pipes and parts. Port B is the one which goes down and only into the base of the tank. Does this mean it's incorrectly piped up? (If so, this is what our landlord suspected the issue was, based on comparing the schemas in the manual with the way the pipes were connected. Apparently the pipes came already connected like this.)

Our landlord has taken the instruction manuals away with him so I am unable to tell you the size and model of heat pump but have taken a photo in case that helps? The outdoors unit is approximately 1m by about 1.5m and a good foot deep. 

I wasn't sure what the manufacturers label you needed to see would be, so took photos of various stickers and labels... Happy to look again if none of these are the right one!

 Again, many thanks Derek.

LG have probably the finest in-room controller of any heat pump manufacturer, with easily adjustable curves for the weather comp, and it's hidden away in the airing cupboard.... 🤨 

53.9 kWh/day for all your domestic electric*, in the coldest of recent cold spells.... It's not brilliant, but at a SCOP of 2.8, possibly, and removing 10kWh/day for other stuff, 122kWh of heat into the property...

Not unreasonable... In a 90% efficient gas boiler, that would have been 136kWh of gas through the meter, or £14/day, or £446 for the month**...

*assuming backstop rates of 34p/unit for electricity

**assuming backstop rates of 10.9p/unit of gas

@ashptenant

Do you know which are the flow and return pipes connected to your heat pump? If you do then see if one of these pipes is connected to port 'AB' on the 3-way valve. If that is not the case then it is possible that your system is not piped up correctly.

I'm afraid that your vacuum cleaner hose is obscuring some of the pipework, and from photo's it is very difficult to see where pipes are connected together.

@hughf I know all fuel bills have risen exponentially lately, but during that time period, the hottest our radiators ever got was 13 degrees, and usually not even that! So I feel very concerned about the efficiency of the system. Either there is a fault of some kind, a set-up issue, or this is the most ineffectual way of heating a home! We have young children and not being able to ever get their bedrooms warm was no joke. We had to use fan heaters every night just to get it warm enough for them to get changed into pj's.

@derek-m I will check and take another photo without the vacuum in the way. Sorry about that. I don't know what the flow or return pipes are, nor how to identify them but will try to take better pictures.

Posted by: @hughf

↑

53.9 kWh/day for all your domestic electric*, in the coldest of recent cold spells.... It's not brilliant, but at a SCOP of 2.8, possibly, and removing 10kWh/day for other stuff, 122kWh of heat into the property...

Not unreasonable... In a 90% efficient gas boiler, that would have been 136kWh of gas through the meter, or £14/day, or £446 for the month**...

 

*assuming backstop rates of 34p/unit for electricity

**assuming backstop rates of 10.9p/unit of gas

I guess what I'm saying is, this huge bill would be easier to bear if we'd actually had heat as a result! Instead, we were running the system as suggested - keeping it on nearly all the time - but with a really cold house and poorly children.

Posted by: @derek-m

↑

@ashptenant

Do you know which are the flow and return pipes connected to your heat pump? If you do then see if one of these pipes is connected to port 'AB' on the 3-way valve. If that is not the case then it is possible that your system is not piped up correctly.

I'm afraid that your vacuum cleaner hose is obscuring some of the pipework, and from photo's it is very difficult to see where pipes are connected together.

Hi again @derek-m,

Further photos. Port AB is the curved pipe in the centre of the valve, which curves down and then out through the wall. It is the uppermost of the grey bound pipes now visible in the photos. I hope these are clearer and more helpful.