UFH to help cooling?

[richo106]

Hi All

 

I have an ASHP, buffer tank,UFH upstairs and downstairs with a manifold for each floor and thermostat for each room.

 

With the few day heat wave we have coming I have always wondered that if I could pump cold water around my UFH it may help with cooling? Has anyone does this and does it work? I’m not expecting it to do loads just help with a degree or 2.

 

if possible what would be the best way with my set up? 
 

any advice/info welcome

 

Many Thanks 

[Nickfromwales]

8 minutes ago, richo106 said:

Hi All

 

I have an ASHP, buffer tank,UFH upstairs and downstairs with a manifold for each floor and thermostat for each room.

 

With the few day heat wave we have coming I have always wondered that if I could pump cold water around my UFH it may help with cooling? Has anyone does this and does it work? I’m not expecting it to do loads just help with a degree or 2.

 

if possible what would be the best way with my set up? 
 

any advice/info welcome

 

Many Thanks 

You may do well to read the hundreds of threads on here that answer this question, and all those to follow   

 

Have a quick search, you'll soon be up to your eyes in info for this subject. 

[JohnMo]

14 minutes ago, richo106 said:

With the few day heat wave we have coming I have always wondered that if I could pump cold water around my UFH it may help with cooling?

If your heat pump does cooling - not all do.

 

But how are you going to control it? Do your thermostats do cooling?

 

Would set flow temp to 14.5 to 16, fixed flow temp, you want the heat pump to run long cycles. I would have all loops open, so if your thermostats do not do cooling, you will need to fool the system by winding the thermostats to max setting a few hours before you expect to get hot. Do not be tempted to go below 14.5 otherwise you are likely to condensation issues.

 

16 minutes ago, richo106 said:

ASHP, buffer tank,UFH upstairs and downstairs with a manifold for each floor and thermostat for each room

Would be looking to simplify that.

[richo106]

Hi @JohnMo

 

My ASHP model is panosonic WH-MXC12J6E5 and does not support cooling, I have just checked this on the controller and the lowest temp it can be set to is 20 deg

 

I am guessing this is now a no go then

 

Cheers 

[JohnMo]

It does do cooling, but have to switch between heating and cooling modes. If you are going down to 20 you are in heating mode. 

[Conor]

In terms of operating, I set mine to a fixed flow temp (13c as our dew point is normally around 10c) and let it run 24x7 with all zones open (expect basement)during the heat wave. it works well. But, I'm in NI and "hot" for us is about 25c. We don't even see 30c here. Yet.....

[richo106]

It does reference cooling, but for the life of me I can’t find anything in the controller/set up to enable cooling

 

[JohnMo]

Download the manual various ways to switch to cooling 

[richo106]

Found it! Thank you

 

As you said I have wound my thermostats out to 35 deg to trick the controller/pump

 

See pics below how I have programmed it to start with to see how I go

 

In terms when I don’t need the cooling do you guys just turn the thermostats off? 
 

Thanks again 

[JohnMo]

47 minutes ago, richo106 said:

terms when I don’t need the cooling do you guys just turn the thermostats off

I have an UFH controller with room sensors. It takes a volt free open/closed contact, to switch between heat and cool, have use a similar contact on the ASHP, instead of the controller.  Then use a single switch to switch everything between heat/cool. Then use the sensor in the room that gets hottest first to initiate cooling - but I run the house as a single zone, with no actuators on the UFH manifold.

 

I do cooling as a seasonal switch over. So it now on until end of September, but only really comes on when it's needed 

[richo106]

Yeh that’s a good setup

I’ll do my summer/winter switchover as usual on my ASHP controller and then just  control the cooling by thermostats.

 

I have set my water temperature for 16deg, I have done a lot of reading on the internet and this seems the lowest it’s seems to recommend to go

is the temperature you continually change? As the dew point would fluctuate wouldn’t it 

 

 

 

[JohnMo]

9 minutes ago, richo106 said:

16deg

Would start there, if you are not getting the cooling effects you want (takes a few hours) you can safely go down to 14ish. Look at your UFH manifold, if you start to see water forming, you have gone too low - it should stay nice a dry.

[SteamyTea]

@richo106

Keep an eye on the buffer tank, that may get condensation.

And let us all know how the cold showers go down, then we know something went wrong in the setup.

[richo106]

1 hour ago, JohnMo said:

Would start there, if you are not getting the cooling effects you want (takes a few hours) you can safely go down to 14ish. Look at your UFH manifold, if you start to see water forming, you have gone too low - it should stay nice a dry.

It’s been on 16 since 12pm, every seems nice and dry. All tanks, manifolds are dry etcc

 

I might tick it down to 15 

 

 

[richo106]

57 minutes ago, SteamyTea said:

@richo106

Keep an eye on the buffer tank, that may get condensation.

And let us all know how the cold showers go down, then we know something went wrong in the setup.

Would the condensation form on the outside of the tank?

 

It’s just done it’s dhw cycle and seemed ok (fingers crossed) and water got to temp 

[richo106]

Delta T on my downstairs loop is around -3/-4 deg 

[SteamyTea]

6 minutes ago, richo106 said:

Would the condensation form on the outside of the tank

If insulated, yes, possibly.

Won't happen on the inside as that is already full of condensated water vapour.

[JohnMo]

4 minutes ago, SteamyTea said:

If insulated, yes, possibly.

Won't happen on the inside as that is already full of condensated water vapour.

Surface temp has to be below localised air dew point - so not that likely.

[richo106]

My humidity (last time I checked) was 38% so safe to say it’s normally around 40%. 
 

If the air temp is 25 deg, it gives a dew point of 10.5 deg so at 15 deg water temp that is a decent gap to avoid any condensation issues 

[JohnMo]

15 minutes ago, richo106 said:

It’s just done it’s dhw cycle and seemed ok

Your 3 way diverter valve will be upstream of the buffer, so buffer will stay cool, while the heat pump moves from cool to heating mode, it will swing the diverter valve, heat cylinder, then swing the diverter valve back and change mode to cooling. You may get a small slug of hot water into buffer.

 

dT sounds fine, it will greep down possibly, mine is currently sitting at 2.3 degs. But it runs at max flow rate while cooling.

[SteamyTea]

7 minutes ago, JohnMo said:

Surface temp has to be below localised air dew point - so not that likely.

Why I suggested keeping an eye on it.

[JohnMo]

3 minutes ago, SteamyTea said:

Why I suggested keeping an eye on it.

Definitely for the first few days until you understand what happens.

[Mike]

4 hours ago, richo106 said:

I have set my water temperature for 16deg, I have done a lot of reading on the internet and this seems the lowest it’s seems to recommend to go

FWIW, French Building Regs say:

• Minimum coolant temperature entering the floor of between 18°C (near the English channel) to 22°C (near the Med), except 16°C if there are humidity controls, dehumidification or similar
• Automatic cut-off if the the coolant drops to 12°C
• No more than 6 circuits per manifold
• Circuits serving bath rooms & shower rooms should be isolated due to the high condensation risk
• Maximum 25 cm between pipes, to avoid excessive variation in floor surface temperature
• Room thermostats set no lower than 26°C

 

Edited 1 hour ago by Mike

[SteamyTea]

57 minutes ago, Mike said:

French Building Regs say

On the face of it they seem quite sensible.