This is my first post on this forum. In a nutshell, I have just had a 10kw valiant another + installed. Having consumed alot of Heat Geek videos and information, I am not sure that the installers have designed and installed the most efficient system so I am looking for some advice on system settings please? Here is the salient info:
Heat loss for house is 8kw.
House 156sqm, 1900’s, but with lots of insulation upgrades to a good standard.
Underfloor heating on 16mm pipes throughout ground floor with 4 room stats and actuators.
Radiator circuit upstairs on thermostat, oversized rads for low temperatures. Radiator circuit on a zone valve to split from downstairs underfloor heating.
Extra pump and mixing valve on the underfloor heating manifold.
28mm pipe to plant room, radiator circuit primary 22mm before short 15mm t’s to rads.
Design temperature 19 degrees (we don’t like a hot house).
Basically I’m wondering how to get the best out of the system as I have come to learn that perhaps the mixing valve on the manifold and the over zoning are not good for efficiencies. Can I run open loop system if I use pure weather compensation and lock the zone valve to rad circuit to manual (always open)? The part I don’t understand really is how to override the mixing valve as I believe that this is bad for efficiencies. Any advice welcomed!
Congratulations getting a heat pump installed! Efficient heat pump operation is all about getting the flow temperature as low as possible, in practice this means setting the weather compensation curve as low a possible while still providing sufficient heat, it may take a while to get this right, @Zarch has done a good blog post on Vaillant heating curve settings, generally the best way to get it dialled in is to keep reducing the curve over a period of days until the house is slightly too cold and then increase it a bit until you’re comfortable:
Heat pumps work most efficiently when they are running low-and-slow for long periods with as many emitters turned on as possible. Therefore, keep all the zones and TRVs open as much as you can by setting the thermostats higher than the set point, this is basically the same as open-loop, if the house gets too hot then reduce the weather compensation curve to reduce the flow temperature. Depending on your UFH floor covering, if you’re able to run a flow temperature of about 45C or less for screeded UFH then consider getting the blending valve and additional pump removed from your UFH since this is not needed if you can run the same flow temperature in rads & UFH.
You can still have a set-back temperature for comfort overnight, but it’s best to not have the set-back temperature more than a few degrees below your desired temperature to avoid the heat pump having to work hard and increase the flow temperature to regain the set point in the morning.
