Which ASHP are set up to cool

[Dan F]

8 hours ago, joth said:

The house is holding a very nice 20-21°C.

We have nice 22C downstairs (family complain any lower than this!).  Really annoyed that I can't turn cooling on/off based on slab temperatue though!

 

8 hours ago, joth said:

The FCU is only 1.5kW not really enough load for a 8.5kW heatpump, wish I'd bought more of them, or a larger one , as they're harder to get now (Brexit and supply chain issues)

That's 1.5kW for each FCU though right?  I get around 1.5-2kW for the whole of the first floor (relative to MVHR supply temp, not internal temp).

 

[gc100]

4 hours ago, Luke1 said:

I have the SMO 20 controller and F2040 8kW heat pump. 

 

I had to enable cooling in the Service menu (Holding the return button for 7 seconds brings up this menu) (At your own risk)

I have no idea if the SMO 40 controller is the same?

 

https://www.nibe.eu/assets/documents/23958/231765-5.pdf (See page 32, your system would be 2 pipe cooling)

I couldn't see anything on the SMO 40 controller about how to enable cooling mode. There was a simple check box on the SMO 20 controller.

 

 

So the installers has just popped over and configured it, so now working in 2 pipe mode. He has set the supply line to 18 degrees which seems high.

 

I questioned him about this and he said any lower and you run the risk of condensation on tiles/under carpets. Seems very high to me. Just wondering what other people are running the temp  at for cooling (UFH)?

[markharro]

Hi @Dan F could you explain what a FCU is? Does it link into a conventional MVHR or ASHP system or is it some sort of standalone device? thanks

 

 

[joth]

44 minutes ago, Dan F said:

That's 1.5kW for each FCU though right?  I get around 1.5-2kW for the whole of the first floor (relative to MVHR supply temp, not internal temp).

 

Yes, it's rated at 1.5kW but in practice I think it's delivering less than that 

Unfortunately I only have one FCU - I bought it on a whim before knowing how well it would work or how much we'd need it. In retrospect buying one mahoosive one would have been simpler, given 200mm air motorised dampers are only about £30 ea on aliexpress

And, we should have installed larger cross section pipework to the loft.

 

 

[joth]

7 minutes ago, markharro said:

Hi @Dan F could you explain what a FCU is? Does it link into a conventional MVHR or ASHP system or is it some sort of standalone device? thanks

 

 

Fan coil unit. On the wet side, you plumb it in just like you would a radiator. (Or even more accurately, like a fan assisted radiator).

 

They have their own thread: 

 

Edited July 19, 2022 by joth

[Luke1]

1 hour ago, gc100 said:

 

So the installers has just popped over and configured it, so now working in 2 pipe mode. He has set the supply line to 18 degrees which seems high.

 

I questioned him about this and he said any lower and you run the risk of condensation on tiles/under carpets. Seems very high to me. Just wondering what other people are running the temp  at for cooling (UFH)?

That's impressive service from your installer! Where in the UK are you based?

I'm sure now its enabled, you can adjust the minimum flow line temperature as you wish in the heating settings menu.

The Nibe recommendation is 18C and if you put anything lower it gives a warning about condensation, but it will still let you set a lower temperature.

 

To prevent condensation build up, you need to know the RH and current temperature. The dew point here is around 11C right now.

 

I am currently running my system at 11C and some condensation is forming on the supply from the heat pump (around parts not insulated in the cupboard such as valves) 

The radiators and floor obviously never get as low as 11C and therefore are not forming condensation. (Albeit there is a slight misting on the radiators) (There is also a risk of any un-insulated pipe runs between radiators etc forming condensation.

 

Once this heatwave has passed I will up the flow to something around 18C and see how the house performs. 

 

[joth]

I have been running the UFH cooling at 14ºC 

 

I have thermistors embedded in the screed and if they ever drop below 15 I have an automation that shuts the UFH pump off until it comes back up. (And inverse threshold for 25º in winter).

This very rarely fires but looks like it was tickled a few times in the last month so I might just tweak the flow temp up to 15.

 

Anyway the floor finishes on top of the screed are alway a few degrees warmer than the sensors/pipes embedded in it.

 

[gc100]

4 minutes ago, Luke1 said:

That's impressive service from your installer! Where in the UK are you based?

I'm sure now its enabled, you can adjust the minimum flow line temperature as you wish in the heating settings menu.

The Nibe recommendation is 18C and if you put anything lower it gives a warning about condensation, but it will still let you set a lower temperature.

 

To prevent condensation build up, you need to know the RH and current temperature. The dew point here is around 11C right now.

 

I am currently running my system at 11C and some condensation is forming on the supply from the heat pump (around parts not insulated in the cupboard such as valves) 

The radiators and floor obviously never get as low as 11C and therefore are not forming condensation. (Albeit there is a slight misting on the radiators) (There is also a risk of any un-insulated pipe runs between radiators etc forming condensation.

 

Once this heatwave has passed I will up the flow to something around 18C and see how the house performs. 

 

 

 

Thanks. I'm in Norfolk - think they happened to be this way.

 

Interestingly (and annoyingly), the pump has turned itself off with the following error "The heat pump is outside its working range. Start again when the outdoor temp has changed"

 

So active cooling has its limits with ASHP in heatwaves at least with my unit. 38 outside here at the moment

[Dan F]

35 minutes ago, joth said:

I have thermistors embedded in the screed and if they ever drop below 15 I have an automation that shuts the UFH pump off until it comes back up. (And inverse threshold for 25º in winter).

This very rarely fires but looks like it was tickled a few times in the last month so I might just tweak the flow temp up to 15.

Do the Ecodan controls not do any dew point calculation?  Vaillant will work out minumum (with a configurable offset) based on RH.

[Dan F]

41 minutes ago, gc100 said:

So active cooling has its limits with ASHP in heatwaves at least with my unit. 38 outside here at the moment

Which ASHP?  Our does cooling up to 46C external.

[Dreadnaught]

2 minutes ago, Dan F said:

Vaillant will work out minumum (with a configurable offset) based on RH.

 

Does that require the optional Vaillant RH sensor I wonder?

[Dan F]

Just now, Dreadnaught said:

 

Does that require the optional Vaillant RH sensor I wonder?

No extra sensor no. The sensoComfort (VRC720) controller has this incorportated

[joth]

1 minute ago, Dan F said:

Do the Ecodan controls not do any dew point calculation?  Vaillant will work out minumum (with a configurable offset) based on RH.

No not at all. The ecodan has no idea about humidity that I've seen. (The mobile app may have it in the weather forecast but that is regional and outside so I wouldn't trust it for much).

I should start logging indoor RHI too and get an idea what the bounds are it sits in

 

 

[gc100]

10 minutes ago, Dan F said:

Which ASHP?  Our does cooling up to 46C external.

Nibe. It might be configurable I suppose

 

[Luke1]

1 hour ago, gc100 said:

 

 

Thanks. I'm in Norfolk - think they happened to be this way.

 

Interestingly (and annoyingly), the pump has turned itself off with the following error "The heat pump is outside its working range. Start again when the outdoor temp has changed"

 

So active cooling has its limits with ASHP in heatwaves at least with my unit. 38 outside here at the moment

I've just had a similar error. The unit is south facing and it is sensor BT28 which causes the unit to shut down above 43C. 

I have now shaded the unit and BT28 is back to 40C with outside shaded air temp being 38C and the unit is working again.

 

Inside temperature is currently 24C which has steadily increased from 22C this morning.

[gc100]

1 hour ago, Luke1 said:

I've just had a similar error. The unit is south facing and it is sensor BT28 which causes the unit to shut down above 43C. 

I have now shaded the unit and BT28 is back to 40C with outside shaded air temp being 38C and the unit is working again.

 

Inside temperature is currently 24C which has steadily increased from 22C this morning.

 

Ah interesting - mine is south facing as well. 

[john0wingnut]

7 hours ago, Luke1 said:

I've just had a similar error. The unit is south facing and it is sensor BT28 which causes the unit to shut down above 43C. 

I have now shaded the unit and BT28 is back to 40C with outside shaded air temp being 38C and the unit is working again.

 

Inside temperature is currently 24C which has steadily increased from 22C this morning.

Mine did the same. Wouldnt work between around 13:00 - 16:00. 
 

set my flow temp to 15 degrees.

 

strangely the degree minutes shot up to 120 and have not changed since. Usually once flow temp is reached it gets back to 0, shuts compressor down, then counts back up before reaching the threshold for inverter to come back on again. 
 

 

[john0wingnut]

7 hours ago, Luke1 said:

I've just had a similar error. The unit is south facing and it is sensor BT28 which causes the unit to shut down above 43C. 

I have now shaded the unit and BT28 is back to 40C with outside shaded air temp being 38C and the unit is working again.

 

Inside temperature is currently 24C which has steadily increased from 22C this morning.

What have you set your cooling dT too for the 20 and 40 degree settings? 
 

Default is 3 and 6 respectively which I find strange as I’m sure with heating the dT it tries to maintain between flow and return is 7-10 degrees C.

[Dreadnaught]

About the cooling resistor for the Vaillant Arotherm ASHP …

 

I just contacted the company who will supply the ASHP and they said "Yes you need a coding resistor for cooling function. It's pretty pricey. About £300 from memory."

 

Anybody know of a cheaper solution? Or did anyone buy it with the resistor already fitted?

 

This video shows the resistor fitting, which, other than the protracted checking-for-a-gas-leak, seem to take about 2 seconds.

 

 

 

Edited July 20, 2022 by Dreadnaught

[Luke1]

10 hours ago, john0wingnut said:

What have you set your cooling dT too for the 20 and 40 degree settings? 
 

Default is 3 and 6 respectively which I find strange as I’m sure with heating the dT it tries to maintain between flow and return is 7-10 degrees C.

I've kept both at the minimum 3C. Because the heat pump only runs for 10-15 mins at a time I thought that it would run at its lowest modulation for longer (and more efficiently) if the delta was lower.

I have no idea if my logic is correct though!

[Dan F]

2 hours ago, Dreadnaught said:

Anybody know of a cheaper solution? Or did anyone buy it with the resistor already fitted?

Our installer supplied and fitted ours.  I can't beleive it's £300, I think some UK resellers are just taking advantage of lack of supply probably.  Where did you get the £300 price from, Vaillant themselves?

[SteamyTea]

35 minutes ago, Dan F said:

Our installer supplied and fitted ours.  I can't beleive it's £300

Do you know the part number?

[Dan F]

6 minutes ago, SteamyTea said:

Do you know the part number?

Yes. 0020269259.  It's available in europe for €30-40 seems.  Somone who needs one should call Vaillant and ask where to get one in the U.K. without being ripped off.

[SteamyTea]

Just now, Dan F said:

0020269259

That should help others.

 

[Dreadnaught]

39 minutes ago, Dan F said:

Where did you get the £300 price from, Vaillant themselves?

 

From the "£300" quote was from the wholesaler, Midsummer Wholesale in this case.

 

The only seller I found was this one, £391.20 inc. VAT. https://www.heatingandbathrooms.com/coding-plug-cooling-function

 

If only we could find the Ω-rating, I bet you could buy one for pennies and solder it oneself.