Hi Mars,

Have you heard anything from Sam recently?

I gave her some details of simple tests she could perform, but have not had any reply. I am not certain if she has seen my message or not.

I have thought of a simple way in which it would be possible to definitely prove whether her ASHP is incorrectly sited or not. But if she does not respond, then I am wasting my time.

@derek-m, I have not heard from Sam, but I have invited to join the forums here, where communication should be a lot easier and more streamlined. I'll follow up with her.

@derek-m

Hi Derek, Sorry you didn't see my replies. I did send a few. I was hoping to be able to find a thermometer but haven't so I will buy one. I am also pursuing my local council over the planning regs; ASHP come under permitted development, but must be 1m minimum from your boundary. Mine is only 80cm so I'm hoping they will have the power to force the builder to relocate it. 

Hi Sam,

No worries, I obviously missed your replies from among the pile.

You will need a thermometer that will go below zero, ideally to -30C if possible.

Make sure you wrap up warm and wear gloves.

Is your ASHP still noisy and not heating very well?

If we can prove that it is pulling in the colder air being discharged by the fan, you should have a very strong case against your builder and installer. I have also thought of a way to prove this. I will send you details if the temperature tests prove positive.

If you have looked at the manual that I sent via Mars, I think that your installers may have followed page 33 'Installation places'. I suspect that this document was actually written for Air Conditioning Units, not ASHP. You can install Air Conditioning Units in enclosed spaces, since it is warm air being discharged, not cold air.

I hope that this helps.

@Derek-m

Thanks for the tip. When outside temps are above 4° the buzz goes and our heating works fine as it mainly just tops itself up. The problem is when its sub 4°.

Good Morning Sam,

It's that Grumpy Old Man (GOM) again.

Once you obtain a suitable thermometer I would suggest that you take the following measurement.

1. Take an ambient temperature reading well away from your ASHP. To be able to compare like for like, take the reading about the same height from the ground as the centre of the ASHP fan. Keep the thermometer in shade so that there is no solar effect and allow a few minutes for the reading to stabilise.

2. Measure the discharge temperature from your ASHP using the same procedure.

3. Measure the intake temperature of your ASHP using the same procedure.

4. Measure the air temperature above your ASHP, about 1 metre from the ground.

5. Measure the air temperature above your ASHP, about 2 metres from the ground.

If you could also send some photo's along with the readings it would be highly useful. 

The readings will hopefully throw some light as to whether your ASHP is badly sited, undersized, or a combination of both.

If I remember correctly, I think that when you first posted, your system was struggling to warm your home even at temperatures above 0C, but its operation has since been improved. Do you know what the technician found wrong or what adjustments he made?

I assume that you live on an estate. Do your neighbours also have ASHP's and are they having similar problems? If so, are their ASHP's installed in a similar location?

Sorry to ask so many questions, it's a technique that I have used for many years to identify the root cause of a problem.

I've attached the performance data for our 14kw Mitsubishi Ecodan ASHP. All data used is from the units software/controller so I can't confirm how accurate this actually is.

@george, how big is your house, e.g. m2 and EPC numbers? Also, you use a lot of hot water; nearly 40% of total cost?  

(I'm getting the same ASHP as yours)

The EPC states 418M2.

Our hot water usage is much higher than average as we usually have 7 people living here and in the last year we had 11 people living here for quite a while so we get through a lot of hot water.

We also had a secondary return fitted when we did our extension and fitted the ASHP and when that’s switched off the 500l unvented cylinder hardly drops 0.5c an hour whereas with the secondary return running it drops around 2-3 degrees an hour so it’s not long before the tank drops from 50 to 45 where it kicks in to heat up the water again. 

Sadly there is very little I can do about this as the pipe runs are potentially 50-80M and it’s not easy to retrospectively beef up the pipe insulation as it also runs under the drive (it was fitted in expensive uponor pipe). If I switched off the secondary return it takes 60+ seconds for the taps/showers/baths to heat up and now everyone is used to instant hot water I’m not sure that would go down well...

@george, thanks and sorry it didn't register with me you're the same George who wrote the review. I'm beginning to think our ASHP (the same as yours) is over-specified for our 165m2 bungalow with only two of us but probably better that way round. I think yours is doing well considering its workload. 

Yep that was my review 🙂 

I think our ASHP is probably under sized for our property but as we are south west facing and have lots of rear glazing and have two log burners we can deal with short spells of cold weather. It’s rare for us to have a long period of sub zero temps in Bedfordshire so we haven’t tested it to it’s limits yet.

Its better to have an overpowered pump than be struggling when you need it most. The good thing with the ecodan is that it’s so easy to adjust the flow temp on your phone/computer using the mel cloud app/site. If you find the ASHP is heating your property with ease flowing at 45 turn it down to 40 or 35 to see if you can achieve similar results as it will reduce your electricity consumption.