Finding ASHP installer who understands fan coils

[flanagaj]

I have spoken to a few local ASHP installers in Hampshire and the moment I mention to them about using the ASHP in cooling mode and having a split system which enables the UFH to be run above dew point in the summer, but have the upstairs fan coils with condensate drains to run at a colder temperature, they just tell me "No, you cannot do that".  Now, I am sure I have read on here, that people are doing just that.

If anyone is doing that, do you have a diagram or even a contact in the Wiltshire/Hampshire/Berkshire/Surrey area of a heating engineer who know and can do what I am trying to do. 

[JohnMo]

Here is a Haier scheme, you just setup as a 2 zone system. Each zone with a different flow temp fixed or WC. The image shows a buffer which is unlikely to be needed

[-rick-]

@SBMS Is in the process of doing something similar so might have a suggestion.

 

Only some heatpump makers (like Panasonic) actively market this as an option so if your installer usually works with a brand that doesn't talk about cooling then it's not a shocker that they are uninformed. Though I tend to think if your business is selling/installing heatpumps then you are doing a bad job if you aren't on top of all the options in the space but this seems par for the course for much of UK installers.

[LnP]

1 hour ago, JohnMo said:

Here is a Haier scheme, you just setup as a 2 zone system. Each zone with a different flow temp fixed or WC. The image shows a buffer which is unlikely to be needed

Pump 1 to the fan coils and pump 2 to the UFH? Is it a given that you need pumps?

[JohnMo]

22 minutes ago, LnP said:

Pump 1 to the fan coils and pump 2 to the UFH? Is it a given that you need pumps?

Mixer is on the UFH heating.  So in heating it is mixing return water to bring down the flow temp, in cooling mixing return water to make supply water warmer than used by the fan coils.  Its just the same as you would do for UFH and radiators.

 

Pumps I would set up a primary and secondary loop, primary loop is just the ASHP circulation pump, for the UFH and fan coils I would have a close coupled tee (CCT) for each circuit, first CCT for the fan coils and second for UFH.  Each circuit from the CCT would require a pump.  So sort of 2 zones one for UFH (mixer as well) and the other fan coils.  Set the two secondary pumps to run fixed speed. Then flow match the primary pump speed to match the combined flow from the 2x secondary.  Fan coils output is governed by fan speed (which is controlled via a thermostat), so the flow can be left to circulate the whole loop, so then run both pumps when ever you have a call for heat/cool.  Otherwise expect to need a volumiser or a buffer.

 

But personally I really wouldn't bother doing fan coils below dew point, save the complication and you can buy something like Jaga Strada Hybrids to do above dew point cooling, no mixer etc.

[flanagaj]

4 hours ago, JohnMo said:

Here is a Haier scheme, you just setup as a 2 zone system. Each zone with a different flow temp fixed or WC. The image shows a buffer which is unlikely to be needed

That image appears to have disappeared and is just a broken link

[flanagaj]

2 hours ago, JohnMo said:

Mixer is on the UFH heating.  So in heating it is mixing return water to bring down the flow temp, in cooling mixing return water to make supply water warmer than used by the fan coils.  Its just the same as you would do for UFH and radiators.

 

Pumps I would set up a primary and secondary loop, primary loop is just the ASHP circulation pump, for the UFH and fan coils I would have a close coupled tee (CCT) for each circuit, first CCT for the fan coils and second for UFH.  Each circuit from the CCT would require a pump.  So sort of 2 zones one for UFH (mixer as well) and the other fan coils.  Set the two secondary pumps to run fixed speed. Then flow match the primary pump speed to match the combined flow from the 2x secondary.  Fan coils output is governed by fan speed (which is controlled via a thermostat), so the flow can be left to circulate the whole loop, so then run both pumps when ever you have a call for heat/cool.  Otherwise expect to need a volumiser or a buffer.

 

But personally I really wouldn't bother doing fan coils below dew point, save the complication and you can buy something like Jaga Strada Hybrids to do above dew point cooling, no mixer etc.

I assume that must make the whole system design much simpler.  I suppose the only down side is that you won't have rapid cooling to hand and if you have a lot of glazing, then on really hot days you may struggle keeping the rooms cool?

[JohnMo]

2 hours ago, flanagaj said:

I assume that must make the whole system design much simpler.  I suppose the only down side is that you won't have rapid cooling to hand and if you have a lot of glazing, then on really hot days you may struggle keeping the rooms cool?

If you want all the cooling now, go for two temperatures, if you want slow and steady cooling just do one temperature. Really depends on the depth of your pockets now and for running costs.  Cold temperatures are just like high heating flow temperatures they take a big chunk out of your expected CoP.

[SBMS]

as JohnMo said with the hydraulic design pretty much but I wanted true cooling so I went fancoils so I can run at proper ac temperatures. 
 

I’ve installed this exact setup with a Panasonic aquarea tcap heat pump. Ground floor is UFH and first (and second floors) are 7x fancoils. All pipework lagged and all fancoils have condensate drains. It took a while to get the design how I wanted it and warrantied with Panasonic. I had an extra towel rail loop that they wanted to make sure was isolated from chilled water so that’s why I couldn’t go off their standard design. 
 

I can run 5 degree water in cooling mode to the fancoils and keep the UFH loop at above dew point (16 degree) as the Panasonic accepts a dual zone temperature control. It’s critical that the heat pump controller actually supports this and Panasonic was one of the few that I found that was big, reputable and would warrant the hydraulic design. I worked with their technical design team to get the design right. 
 

it fundamentally works by having two circuits off the buffer (sorry but yes, Panasonic mandate a buffer for hydraulic separation in this system design). In cooling mode, heat pump can chill the buffer to 5 degrees. That loop is pumped straight to any FCUs that demand cooling. The second loop to the UFH has an inline temperature sensor and a 3 way mixing valve. The temperature sensor connects back to the heat pump controller and that makes sure that water leaving to that circuit is blended up with return water to a safe minimum temperature. If the circuit stabilises at say 16 degrees the zone valve closes to prevent the circuit going any colder. 
 

it’s a pretty simple setup really. I had additional complexity because the towel radiators are on the same circuit as UFH. There’s a zone valve I installed before this circuit that is controlled by loxone relay so in summer I just deactivate this. You could Do this with a heating controller as well (or a switch!). 

[SBMS]

My hydraulic design in case it’s useful. 100% possible. Find a certified Panasonic installer and your installer would do as mine did and defer to Panasonic technical to do the design. They just install. If it’s wrong it’s on Panasonic so as long as they follow the schematic they are covered.