I bought a Heat Pump

TheMaster_2

Reed_Richards said:

TheMaster_2 said:

I had a Mitsubishi Ecodan ASHP installed last year, I also installed solar and batteries.....
I have noticed a huge difference with the ASHP compared to my old gas heating system, the house is colder downstairs. I have tried different flow temperatures. Downstairs just does not get warm to 3 radiators for some reason I

You imply (by not mentioning it) that you did not get new radiators when you got the heat pump.  If so that was probably a big mistake as it is unlikely that your existing radiators have enough output at the lower water temperature that the heat pump provides.  Nonetheless, the problem you describe has a standard solution that applies to all central heating systems, whatever the "boiler".  The standard solution is to adjust the radiator valves to reduce the flow rate to the "hot" radiators and increase the flow rate to the "cold" radiators (assuming those radiator valves are not already fully open).  If you have Thermostatic Radiator Valves you can adjust these to achieve the same effect but upstairs will have to reach temperature before downstairs warms up.

I replaced almost all my radiators but chose not to replace the radiator in my kitchen because of lack of wall space, despite the fact that the calculations said that I needed one with a bigger surface area.  The consequence is that first thing in the morning the kitchen can be a bit chilly.  It warms-up during the day but more slowly than the other rooms in the house. 

Sadly, if you replaced a gas boiler with a heat pump you will find yourself paying more to heat your house . If you were told otherwise you were mis-sold the heat pump.  

Hi sorry I should have said, most of my radiators were replaced the only one that was not was one that I had just replaced a couple of months earlier as we deemed as the correct size on the survey. I have tried balancing the radiator valves but it seems to make little difference, I am still thinking it's more of a pipework issue.

Reed_Richards

TheMaster_2 said:
Hi sorry I should have said, most of my radiators were replaced the only one that was not was one that I had just replaced a couple of months earlier as we deemed as the correct size on the survey. I have tried balancing the radiator valves but it seems to make little difference, I am still thinking it's more of a pipework issue.

15 mm pipes should be fine; I'm told microbore pipes are no good.  Do the radiators themselves get hot as fast as the others and is it just that the rooms stay cold or do the radiators remain tepid.  Do your radiators have (new) TRVs?       

matelodave

If the rooms dont get warm enough then something isn't right - either the flow temp is too low, the rads are undersized, the unit might be too small or you arent operating the system correctly.

What is the temperature of the radiators (flow and return) - one of these would help - https://www.amazon.co.uk/Thermometer-Temperature-Bimetal-Stainless-Surface/dp/B01N8SQS54/ref=bmx_2?pd_rd_w=Qntq8&pf_rd_p=6398e171-4f42-4318-a493-6aac0e34c3e5&pf_rd_r=F5KTQ0RBG0XYGA8DAZTH&pd_rd_r=62c3a2f4-7d1d-4945-ada6-f9615fd765fd&pd_rd_wg=oVcBB&pd_rd_i=B01N8SQS54&psc=1 (or you could get two and put one on each end of the rads to check the temperature across them).

 Have you tried doing your own sums based on the room heat requirement, radiator specs and temperature. Replacing the radiators is fine if they were replaced with suitably rated units.

I know thats what the heating company should do, but it helps your understanding of the system if you can get your head around some of the fundementals and at least try an eliminate some of the obvious problems. The sums are easy and there are online calculators which help you calculate room heat requirements - your system specification should have all the info, so all you need to do is check that it's reasonably correct.

Reed_Richards

Yes, if some rooms are cold that did not used to be cold with your old gas boiler then there is a range of possible explanations but I believe if you set about a systematic investigation you might be able to get a good idea of the root cause of the problem and then fix it.  I had a problem with some radiators in one room that turned out to be an air lock but my installer fixed it by turning off all other radiators at their TRVs.  That concentrated all the pump power in that one bad area, forced the trapped air out of the pipes and into the radiators where I could bleed it out and thereby cleared the problem - so it only lasted about 10 minutes. 

TheMaster_2

Reed_Richards said:

TheMaster_2 said:
Hi sorry I should have said, most of my radiators were replaced the only one that was not was one that I had just replaced a couple of months earlier as we deemed as the correct size on the survey. I have tried balancing the radiator valves but it seems to make little difference, I am still thinking it's more of a pipework issue.

15 mm pipes should be fine; I'm told microbore pipes are no good.  Do the radiators themselves get hot as fast as the others and is it just that the rooms stay cold or do the radiators remain tepid.  Do your radiators have (new) TRVs?       

The rads with the problems get hot at the top and are just warm at the bottom. I have an IR temp reader camera. I was running the flow temp at 46 IIRC at the time I took these. All TRVs were new. Upstairs works a treat as I said it gets nice and warm. These rads seem to take the longest to get warm as I believe the loop goes upstairs first then downstairs. I am also not convinced the radiator that was left in (my new rad) is sufficient for the size of the room anyway as the same size room (kitchen) has 2 rads 1 large the same as the lounge and a smaller one, (however, turned the smaller one off in the kitchen as my missus is always cooking something in the oven!). Hope that makes sense
Is there room for the size of the radiator calculator for ASHP? 

Upstairs

Small bedroom 1         46/42

Master bedroom         46/41

Large Bedroom 2         45/40

Downstairs

Lounge                        40/25

Kitchen Rad 1              37/25

Kitchen Rad 2 Turned off (I turned this on as well to see if it makes any difference – it didn't!)

Bathroom                    30/24

shinytop

@TheMaster_2, you say 3 of your rads never get hot.  That's not necessarily an ASHP problem. It could be an airlock or pipework problem or something to do with your thermostat.  Where is your thermostat - is it portable/wireless?  If the thermostat is in a warm place, then when that place heats up to temperature the system will just shut down even if the rest of the house (or zone if you have separate ones) is still cold.   Even 50 deg radiators will feel a little hot to the touch.  

Are you receiving RHI?  If so your supplier should have done all the calculations using MCI standards and your radiators should reflect that.  If you want to check radiator sizing, this is quite a good guide.
http://starsapp.co.uk/basic-heat-loss-calculator/

This all sounds ike a problem your supplier should be fixing.
 

Reed_Richards

Radiators that are hot (or hotter) at the top than at the bottom have too low water flow.  In an old central heating system that might be due to a build up of sludge (from internal corrosion) but if your radiators are new then it is more likely that the pump that circulates the heating water is not pumping fast enough.  You can prove this one way or another by temporarily turning off the upstairs radiators (after first noting what setting you had each TRV at).  If that improves the downstairs radiators that points towards a pump issue rather than a sludge issue.  My system has two pumps, one for the central heating inside the airing cupboard and another inside the heat pump unit.  But I have 14 radiators rather than your 7.  There is also a flow gauge/regulator inside the airing cupboard.

If your heat pump was installed to MCS standards you should have a report on each room giving the output of each radiator and how that matches the requirement of each room.  

matelodave

This is quite a good website and have a play with the heating simulator https://heatpumps.co.uk/heating-simulator/ to see what happens with flow rattes and rad sizes

The ideal flow/return differential for a heatpump is around 5 degrees. The upstairs rads look about right but you've got a problem downstairs. Either an air lock, a blockage or even the rads are far too big because the heat difference between flow and return is far too high, you need to get it closer to 5 degrees, Can you get the temps better balanced  across the downstairs rads if you turn the upstairs rads off or right down. Even the flow temps downstairs are a lot lower than upstairs

We had a problem in a previous house where a couple of upstairs rads had high flow rates and were robbing other rads. In the end if you have say, 10 kw input and then suck 5-6kw out upstairs it only leaves 4 kw for downstairs which is presumably where you need most heat

TheMaster_2

shinytop said:

@TheMaster_2, you say 3 of your rads never get hot.  That's not necessarily an ASHP problem. It could be an airlock or pipework problem or something to do with your thermostat.  Where is your thermostat - is it portable/wireless?  If the thermostat is in a warm place, then when that place heats up to temperature the system will just shut down even if the rest of the house (or zone if you have separate ones) is still cold.   Even 50 deg radiators will feel a little hot to the touch.  

Are you receiving RHI?  If so your supplier should have done all the calculations using MCI standards and your radiators should reflect that.  If you want to check radiator sizing, this is quite a good guide.
http://starsapp.co.uk/basic-heat-loss-calculator/

This all sounds ike a problem your supplier should be fixing.
 

Yes agree it could be either pipework or an airblock. The thermostat (wireless) is downstairs in the hallway so it's not that. The ASHP stays on until the downstairs does get to temp which I usually set to 20 during the day and 18 on a night.

Yes receiving RHI. Yes they did the calculations. However, I as mentioned earlier one room the same size as my lounge has 2 rads, one the same size and an additional smaller rad.
They have mentioned adding another pump, however, I am concerned about the pump noise when we are sleeping, which they did agree would be an issue.
I am hoping to have a call with the installers this week to come up with a plan.

Reed_Richards

TheMaster_2 said:

They have mentioned adding another pump, however, I am concerned about the pump noise when we are sleeping, which they did agree would be an issue.
I am hoping to have a call with the installers this week to come up with a plan.

Yes, pump noise in the room next to the airing cupboard is a a problem for me, the rest of the house is acceptably quiet.  I am awaiting some adjustments which I hope will reduce that noise.  I allow the house to cool by a few degrees and night so the pump is off until sometime between 4 and 6 am but you don't want to be woken up then.  Although in my old house we slept in a room above the gas boiler and got used to the noise that that made.