Heatpump in cooling mode

[Dave Jones]

As its actually nice today, tried out running the heatpump in reverse to cool the house.  To keep above dewpoint (home assistant takes care of this) set at 16C, had the slab down to 16 within 4 hours and the house is noticeably cooler when walking inside. Have 5 panasonic fancoil units in the bedrooms which will test once the painters are done.

 

[Nick Laslett]

3 hours ago, Dave Jones said:

… To keep above dewpoint (home assistant takes care of this) set at 16C…

@Dave Jones in this context what is the “home assistant”?
 

I just managed to get my ASHP installed in time for the April cold snap where it hit 2° overnight for 3 days in a row in Suffolk. Now looking forward to some hot weather to test the cooling. 

[The Bin Man]

Just wondering but does the cooling only work effectively with UFH systems?  Can radiators make an effective contribution?  

[garrymartin]

1 hour ago, Nick Laslett said:

@Dave Jones in this context what is the “home assistant”?

Open source home automation software - https://www.home-assistant.io/

[jack]

1 hour ago, The Bin Man said:

Just wondering but does the cooling only work effectively with UFH systems?  Can radiators make an effective contribution?  

 

You can get fan-assisted radiators that can be used for cooling. I'm sure one or two people have mentioned using them.

To be honest, I think you'd be better of with aircon in most cases, given the cost per radiator of this type.

[Dave Jones]

10 hours ago, jack said:

 

You can get fan-assisted radiators that can be used for cooling. I'm sure one or two people have mentioned using them.

To be honest, I think you'd be better of with aircon in most cases, given the cost per radiator of this type.

 

not really. aircon is going to be 5-10x more expensive than fancoil units.

[Dave Jones]

11 hours ago, The Bin Man said:

Just wondering but does the cooling only work effectively with UFH systems?  Can radiators make an effective contribution?  

 

your existing emitters are perfectly adequate for cooling, if your close to passive and have no upstairs heating then the addtion of fancoil units is a cheap and quick option.

[JoeBano]

1 hour ago, Dave Jones said:

 

your existing emitters are perfectly adequate for cooling, if your close to passive and have no upstairs heating then the addtion of fancoil units is a cheap and quick option.

Have you used insulate your pipe work with vapour barrier? That’s always put me off swapping my rads with fan coil units. 

[Dave Jones]

2 hours ago, JoeBano said:

Have you used insulate your pipe work with vapour barrier? That’s always put me off swapping my rads with fan coil units. 

 

why do you want a vapour barrier for pipes ?

[ancient tony]

Great - the reason I joined!

I have a Samsung AW heat pump, fitted earlier this year  (by chance on the coldest days of the winter just to remind us what a cold house is like). It was fitted totally free - including solar panels as my wife is disabled, so I had to accept what I got - which included basic settings.

It is radiator only.

 

I have need for cooling just one or perhaps 2 rooms as my wife can't tolerate heat.

I have studied the Samsung user manual and find little to help work out how to turn it cold.

I fitted a thermostat  which surprisingly made it display cooling where it only showed heating before.  I had to change one setting to tell it I wanted heat and cold.

 

If I turn the thermostat to demand cooling the water circulates but the heat pump does not start.

I am thinking the device thinks I don't need it on until the outdoor temperature is hot enough for whatever pre-set notion Samsung have.

The Water Law (climate control) just has temperatures that set the lower and higher limits of it's water law algorithm - but surely it can work outside these. In heating mode you set similar parameters but if the outside temperature falls below or above these it will still work. I changed the lower setting to it's minimum 25 degrees, today has been 21 C so it may be I have to wait for the anticipated hot spell.

I would really appreciate any help.

 

[JoeBano]

6 hours ago, Dave Jones said:

 

why do you want a vapour barrier for pipes ?

Condensation risk, last year I was getting wet patches on my floor in the garage from the Ufh manifold on humid days which i wasn’t bothered it’s in the garage. I can set my heat pump to adjust cooling flow temperature to dew point but I need another sensor 

[sharpener]

On 10/05/2024 at 16:54, ancient tony said:

I would really appreciate any help.

 

Tell us the exact model of HP you have, someone else may have the same.

 

Have you got the manual or looked on line for it?

 

On 10/05/2024 at 16:54, ancient tony said:

I had to change one setting to tell it I wanted heat and cold.

 

May be necessary but not sufficient! On Vaillants you also need to insert a special programming plug. Or perhaps the scheme under which you got it for free doesn't allow cooling for some bureaucratic reason so it has been disabled.

[JohnMo]

On 10/05/2024 at 16:54, ancient tony said:

radiator only.

Cooling may not be very effective with radiators as the water just stays at the bottom of the radiator.

 

On 10/05/2024 at 16:54, ancient tony said:

fitted a thermostat  which surprisingly made it display cooling where it only showed heating before

A thermostat when in heating or cooling mode just switched it's own logic for call for heat. You need a setting change in the heat pump to make it cool. 

 

On 10/05/2024 at 16:54, ancient tony said:

Water Law (climate control) just has temperatures that set the lower and higher limits of it's water law algorithm - but surely it can work outside these. In heating mode you set similar parameters but if the outside temperature falls below or above these it will still work. I changed the lower setting to it's minimum 25 degrees, today has been 21 C so it may be I have to wait for the anticipated hot spell

I would reset to your original settings, those settings are for heating, I suspect the 25 degs is min flow temp. When in cooling mode the parameters change to ones suitable for cooling.

 

Some heat pumps are sold without cooling as standard, but all can do it, some need additional bits to make it work. Mine needs a zero volt switch to move it from heating to cooling.

[Dave Jones]

On 10/05/2024 at 17:54, JoeBano said:

Condensation risk, last year I was getting wet patches on my floor in the garage from the Ufh manifold on humid days which i wasn’t bothered it’s in the garage. I can set my heat pump to adjust cooling flow temperature to dew point but I need another sensor 

 

vapour barrier wont help. 

 

I have set our to be dew point +2c automatically in home assistant. 

[Jymmm]

What thermostat and dew sensor are you using Dave? Interested to know how have you implemented as ive been thinking of doing the same with home assistant.

[ancient tony]

On 12/05/2024 at 00:02, sharpener said:

 

Tell us the exact model of HP you have, someone else may have the same.

 

Have you got the manual or looked on line for it?

 

 

May be necessary but not sufficient! On Vaillants you also need to insert a special programming plug. Or perhaps the scheme under which you got it for free doesn't allow cooling for some bureaucratic reason so it has been disabled.

Thanks for your reply.

 

I have a slight water leak (outdoors so not too worried)- so phoned the installer to get it sorted - and asked about any changes to get it to cool - he obviously only knows the settings he was told to make and said "that would be good if it could cool".

 

I have a Samsung Eco - 8Kw. I have the manuals - which are good bedtime reading. The only settings to make it work in cold mode seem to be to change it from "heat only" to "heat and cold".

The "waterlaw" has two parts - one for heating and the other for cooling. For cooling the only figures that seem relevant are the temperature the waterlaw takes over with it's lowest output (the minimum outdoor temperature) and the higher value when the pump will be on full output. The lower, when the waterlaw provides the lowest output has a minimum of 25C, which is why I do wonder if it will not start working under that outdoor temperature.

It is possible to alter some other variables such as the pump's out temperature but unless it works at all that is immaterial.

If it does work then perhaps sometime I would change the radiator to one that has a fan - I wonder if they also have the water in at the top and out at the bottom as that would force the cold water to spread across the radiator to some extent.

I am considering setting the temporary thermostat I have fitted to demand cooling and holding a hot water bottle on the outdoor thermistor to fool it into thinking the outdoor temperature is higher and see what happens.

 

I will come back to update on the progress. I hope I have not messed up the original post, but it seemed appropriate to confine cooling issues to this thread until more people are asking bout cooling.

 

 

 

[eniacs]

I have been using my mitsubishi in cooling now for about a month. All pipes lagged with type q insulation and fan coil rads in use that are designed for cooling.

 

We also have normal rads in place for winter heating in a few rooms, these are totally useless at cooling, they create pools of condensation and the cold water only flows in the bottom of the rad.

 

Fan coils are perfect for it however. If installing a new heating system and you are well insulated, may be worth adding to create cooling in the summer.

[LnP]

6 hours ago, eniacs said:

I have been using my mitsubishi in cooling now for about a month. All pipes lagged with type q insulation and fan coil rads in use that are designed for cooling.

 

We also have normal rads in place for winter heating in a few rooms, these are totally useless at cooling, they create pools of condensation and the cold water only flows in the bottom of the rad.

 

Fan coils are perfect for it however. If installing a new heating system and you are well insulated, may be worth adding to create cooling in the summer.

The fact that you get condensation under your rads must mean you're running the HP flow temp colder than the dew point in the house? Are you concerned about that at all? Do the fan coils collect the condensate and drain it somewhere? What is type Q insulation, does it keep the moist air away from the cold pipes?

[JohnMo]

Just looked at our fan coil, it's being supplied with about 12 Deg water same as the UFH, no condensation at all. Fan coil pipes aren't insulated.

[LnP]

34 minutes ago, JohnMo said:

Just looked at our fan coil, it's being supplied with about 12 Deg water same as the UFH, no condensation at all. Fan coil pipes aren't insulated.

Interesting. I'm at the design stage for my self build and do want active cooling but still thinking how to do it - heat pump or multi-splits. According to my cheap electronic air quality analyser (CO2, temp and rel humidity), the air in the room right now is 20^oC and 65% relative humidity. A psychrometric calculator or chart indicates that the dew point is 13^oC. So I'd be getting condensation if I was running the HP with a flow temp of 12^oC. Using the heat pump for cooling is attractive, but I'm worried about condensation in hidden places - mould, rot etc.

Edited May 15 by LnP

[JohnMo]

22 minutes ago, LnP said:

psychrometric calculator or chart indicates that the dew point is 13^oC. So I'd be getting condensation if I was running the HP with a flow temp of 12^oC. Using the heat pump for cooling is attractive, but I'm worried about condensation in hidden places - mould, rot etc.

 

Just checked the house dew point and it's about 14.5 degs currently, the UFH manifold is just feeling cold but looks dull so some water is starting to form. But I operate cooling for 3 hrs in the morning and 3 hours in the afternoon with 1.5 hrs off around midday, allows for hot water production, but also keeps me mostly away from dew point.  Flow temp starts at about 17 and takes the cooling period to get down to 12. Found last year if you try to leave it cooling all day you start to get drips from the UFH manifold. If I run any warmer the heat pump cycles too much. At 12 Deg set point it run non stop the whole cooling session.

 

Also found last year UFH cooling really just helps temper the temperature and stops the extremes, rather than real cooling. Our living room is currently 25.6 at 1.5m high and it's 23 in the hall at 0.5m high, but feels more like 22. The floor is pulling the heat from your body, similar to wind chill in some respects. Humidity is 56% in the house (MVHR) and the summer house where the fan coil is is 52% (with dMEV). Without underfloor cooling the room with all windows and blinds closed gets to nearly 28, because of the wall of glazing. Windows and door will be opened to purge the hot air in a while.

[ReedRichards]

Just to remind everyone, if you had your ASHP fitted without planning permission as a permitted development then it should not be used for cooling.  To be clear, this does not apply to new builds where the planning permission covers the entire build including the heat pump.  

[Dave Jones]

On 13/05/2024 at 12:35, Jymmm said:

What thermostat and dew sensor are you using Dave? Interested to know how have you implemented as ive been thinking of doing the same with home assistant.

 

using a switchbot, 2 actually, 1 upstairs 1 down. 

 

https://uk.switch-bot.com/pages/switchbot-meter-plus

 

 

Made a simple automation to fire the Aquera and move target temp to dewpoint+2

Edited May 19 by Dave Jones

[eniacs]

On 15/05/2024 at 15:38, LnP said:

The fact that you get condensation under your rads must mean you're running the HP flow temp colder than the dew point in the house? Are you concerned about that at all? Do the fan coils collect the condensate and drain it somewhere? What is type Q insulation, does it keep the moist air away from the cold pipes?

 

Designed the system for it. Rads are off in cooling mode. Fan coils designed for cooling and condensate collected.

 

On 15/05/2024 at 15:45, JohnMo said:

Just looked at our fan coil, it's being supplied with about 12 Deg water same as the UFH, no condensation at all. Fan coil pipes aren't insulated.

My fan coils are designed for a flow temp of 7 deg. I tried higher temps but couldnt get the house temps down. Gave up and reduced the flow temp lol, luckily my pipes are fully lagged.

 

On 18/05/2024 at 05:26, ReedRichards said:

Just to remind everyone, if you had your ASHP fitted without planning permission as a permitted development then it should not be used for cooling.  To be clear, this does not apply to new builds where the planning permission covers the entire build including the heat pump.  

This must be hard to police.

[JohnMo]

23 minutes ago, eniacs said:

My fan coils are designed for a flow temp of 7 deg. I tried higher temps but couldnt get the house temps down.

Mine really is massive for the room it's in, it's also 4 pipe version (so two heat exchangers) that I piped in series to almost double the heat exchanger area. This allows a flow temp of around 32 for heating and around 12-13 for cooling.