Andrew Posted September 23, 2019 Share Posted September 23, 2019 Just in the process of getting some UFH quotes as we'll need the pipe fairly shortly to put in the slab. I've had a couple of quotes, one of which didn't include a pump set for the manifolds. When I queried this they said that as we're using an ASHP we don't need the pump at the manifold. The other quote also knows we plan to use an ASHP and has included the pumps in the quote. The plan is to use an ASHP as the source for UFH and DHW. The UFH will be split across 3 manifolds. What's the normal way to do this - is the pump at the manifold omitted when using an ASHP? Link to comment Share on other sites More sharing options...
ProDave Posted September 23, 2019 Share Posted September 23, 2019 Definitely get a pump in each manifold. Some ASHP's require quite a high water flow rate through them and it can be quite hard just to achieve the flow rate they need (I had to fit an extra circulating pump). The last thing you want to do is restrict the flow even more by expecting the ASHP's pump to push water around the UFH pipes. 1 Link to comment Share on other sites More sharing options...
Jeremy Harris Posted September 23, 2019 Share Posted September 23, 2019 +1 to the above. We've found that one advantage of being able to pump water around the UFH with the heating/cooling off, just using the manifold pump, is that tends to even out the floor temperature. In summer this can help to redistribute heat around, so that parts of the floor than may get hot from the sun shining in get cooled a bit as that heat is shifted around to the rest of the house. It can make a significant difference at times, because just reducing the temperature of a patch of floor by a few degrees can significantly reduce the heating effect this has on a hot day. Link to comment Share on other sites More sharing options...
Adam2 Posted September 23, 2019 Share Posted September 23, 2019 How do you control the pump when just recirculating the water (with no heat/cool activated on the ASHP)? Are the pumps running 24 x 7? Link to comment Share on other sites More sharing options...
Jeremy Harris Posted September 23, 2019 Share Posted September 23, 2019 2 minutes ago, Adam2 said: How do you control the pump when just recirculating the water (with no heat/cool activated on the ASHP)? Are the pumps running 24 x 7? The pump turns on and off from the programmer, so whenever heating/cooling is scheduled to be on, the pump runs. The ASHP fires up in either heating or cooling mode when both the programmer is on and one of the thermostats is calling (there's one thermostat for heating, another for cooling, set with different thresholds). Link to comment Share on other sites More sharing options...
Adam2 Posted September 23, 2019 Share Posted September 23, 2019 Thanks - though I was curious about the operation of the pumps when the heating/cooling is off??? Link to comment Share on other sites More sharing options...
Jeremy Harris Posted September 23, 2019 Share Posted September 23, 2019 4 minutes ago, Adam2 said: Thanks - though I was curious about the operation of the pumps when the heating/cooling is off??? If the programmer is off, then the pump turns off, and the thermostats cannot fire up the ASHP either. The programmer is just a standard central heating one, with the heating channel turning the power to the circulating pump on and also providing the power for the thermostats, so with it programmed off the heating/cooling is off, with it programmed on, the circulating pump runs, and if a thermostat calls for heating, or calls for cooling, the ASHP will fire up from the thermostat call. Link to comment Share on other sites More sharing options...
Adam2 Posted September 23, 2019 Share Posted September 23, 2019 Great thanks - got it now ? Didn't realise that the pump would run just because the timeslot is "on" without also needing the thermostat to require heat/cool - though of course it must as you can have multiple sensors off 1 manifold for different rooms. Will have a look at programmers that support time slots set for both heating and cooling - is that a common feature? Mind sharing which model you are using? Link to comment Share on other sites More sharing options...
Jeremy Harris Posted September 23, 2019 Share Posted September 23, 2019 The programmer I used is just a standard single channel Drayton LP111, the thermostats are Computherm Q7RF wireless units (there are two, one controls heating, one controls cooling). The programmer doesn't select heating or cooling, the thermostats do that. The programmer just sets when the system is on or off. This also gives an easy way to just turn the thing off when on holiday. Our house is a passive house, with a very long thermal time constant, so room zoning would have been pretty pointless, as it takes well over a day to drop by 1°C, and trying to change individual room temperatures on the fly just wouldn't work. We have no heating upstairs, just towel rails in the bathrooms that come on for a couple of hours, morning and evening, and that ensures that the bedrooms stay slightly cooler than the living rooms. 1 Link to comment Share on other sites More sharing options...
Adam2 Posted September 23, 2019 Share Posted September 23, 2019 Thanks again - lot of thinking to be done, my plumber and electrician will hopefully get their heads around this - though plenty of time for that.... Link to comment Share on other sites More sharing options...
Andrew Posted September 23, 2019 Author Share Posted September 23, 2019 OP here. Thanks for the replies. I’ll get them to add the manifold pumps to the quote. Link to comment Share on other sites More sharing options...
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