Heat Pump issue

[Sarah2901]

Hi,

I moved into a house which already had an ASHP installed (where we live there is no gas or I would have already changed to gas!). The house is a detached 1970’s dormer with 4 bedrooms. It has insulating wall paper and polystyrene blocks in the loft on the roof but I’m not sure it’s suitable for ASHP really in terms of insulation. Our electric bills are pretty huge.

The heat pump is Daikin (this link is the installation manual https://www.daikin.co.uk/content/dam/document-library/declaration-of-conformity/heat/air-to-water-heat-pump-high-temperature/ekhbrd-abv1/EKHBRD-AB(V1-Y1)_EKHBRD-AC(V1-Y1)_4PW60970-1F_Declaration of conformity_English.pdf). When we moved in there was no thermostat anywhere. The water temperature was set to 60 degrees and each radiator had it’s own standard thermostat valve on it. We installed a netatmo thermostat and put smart valves in the rooms we care most about (kids bedrooms). We always have all the thermostats set to 18-21 degrees depending on time of day. We have the hot water come on for an hour a day which is also powered by the heat pump. Our downstairs radiators go off the upstairs ones in a giant single loop (at some point there must have been a leak downstairs and the previous owners didn’t want to pull up the concrete floor to redo the plumbing and so they just put pipes going through the ceilings to upstairs...).

6 months ago I had 3 radiators upstairs replaced with column radiators (only because they look nice) but I thought this would be good for the heat pump as large radiators with lower temperature is recommended(?)

Ever since then a huge radiator in the lounge didn’t work. At some point the radiators in the dining room also stopped working. A month ago we realised the thermostat valves (old style manual ones) in our bedroom weren’t working and the pins were not popping out when pressed in. We had the system drained and new thermostatic valves fitted. Since then heat returned to one radiator in the dining room but the cold has spread to the utility room and our large kitchen extension.

So downstairs we have hardly any heating at the moment and are using an oil filled plug in radiator. Upstairs is ok but the columns never get as hot as the normal radiators - they heat the rooms fine though. We had a few plumbers here and no one knows what is wrong. Most people won’t touch it because they are not certified in heat pumps and the heat pump people blame the radiator plumbing.

we have tried:
* switching off all rads except for the kitchen ones to try to clear an air lock
* bled all radiators in the house
* check all lock shield valves are open

anyone know what could be wrong or have any advice? Could there be dirt in the system? I would have thought sludge would build up more gradually... I’m so tired of being cold!

 

[JohnD]

If I search for the problem buried in your post, I think this is the heart of it.

Am I right?

6 months ago I had 3 radiators upstairs replaced with column radiators (only because they look nice) but I thought this would be good for the heat pump as large radiators with lower temperature is recommended(?)

Ever since then a huge radiator in the lounge didn’t work. At some point the radiators in the dining room also stopped working.

What month did you notice the heat pump was not warming your house sufficiently?

I think you say you have tried turning off all the hot radiators. Is that right?
When you do that, does the heat pump continue running and making its pipes hot? And do any radiators now get hot?

Have you got a hot water cylinder? What colour? Is the tapwater surprisingly hot?

 

[Sarah2901]

Yes - turned off all the hot ones to try to push any air lock through. Heat pump continues running - it seems fine and was serviced just before the winter. The main pipe into the heating remains hot. One of the radiators gets warmer when I do this but not hot. When I turn the other radiators back on again it reverts to how it was before and the radiators go cold again.

we have a blue hot water cylinder in the airing cupboard. It looks old and I doubt it was replaced when the ASHP was installed. It has an electric immersion on it but we have only used this when the ASHP was broken once. The tap water is pretty hot but I wouldn’t say overly. We only have the water on for an hour a day and at the end of the day we have usually used it all - bit of washing up and a bath for the kids generally uses up the tank.

 

[JohnD]

feel the hot pipe coming out of the pump. Feel the flow pipe going into the cylinder from the heat pump, and the flow pipe going into the only warm radiator.

How do the temperatures of these three pipes compare?

What month did you notice the heat pump was failing to adequtely heat your house?

Was it satisfactory last winter?

 

[Sarah2901]

I can’t tell which pipe is the one coming out of the heat pump - hard to get to and loads of pipes. There are a couple which are pretty warm... the pipe into the cylinder is hot. I can hold it just about. Pipe going into a working radiator is little less hot but still hot. It’s quite close to the cylinder - next room.

currently the radiators upstairs work (3 normal convection of varying ages, 2 towel radiators and 3 column radiators - columns not getting hot to touch but sufficient to heat the rooms. Downstairs I have 3 radiators out of 9 working.

the first radiator went cold right after the column radiators were installed in May 2019 but it was the lounge and we have a wood burner so wasn’t that bothered. The dining room went cold between then and December (never use this room so didn’t notice for ages). The kitchen only went cold in the last month - right after the system was drained to fix the thermostat valves upstairs.

last winter (2018/2019) it was all ok! Radiators all nice and hot.

I wonder if we need the system flushed maybe? Some of the rads are ancient and the water is dirty when I bleed them. Maybe all this work has dislodged the dirt and pushed it around. Trying to find someone who will flush it including the heat exchange in the pump is a whole challenge in itself though. Plus it’s expensive if it doesn’t fix it though at this point I am happy to spend!