The underfloor heating is controlled by 2 x heatmiser uh8-rf control units and 8 room thermostats. These control 12 Ambiente Actuator Valves on the manifold.
I am trying to set the system up such that the heating is controlled by 1 room thermostat (family room).
The Ambiente actuator valves has a commission clip, which holds the valve permanently open (the red bit)
The valve contains a wax element, which on receipt of a signal from the thermostat (normally via a wiring control box), the valve will open, allowing the warm water to flow through the relevant pipework loop.
If all the circuits, except the family room, are held open with the red clip fitted, would that work?
Yes the commissioning clip will hold the actuator open, or you could just unscrew/remove them all to be sure they are fully open (including family room) and/or if this is to be permanent, unwire them too - in fact, if there’s no other good reason for zoning (bedrooms, high solar gains etc) you could do away with all the third party stats/controls and just dial in the heat pump weather compensation curve and UFH zone flow rates, so the flow temperature matches the heat loss - if you’re using a stat to switch off the heat pump, then the flow temperature maybe too high and efficiency could be improved. I would generally run the UFH 24/7, just set up the heat pump to switch off the heating when it goes above say 10-15 degC outside, depending on the house insulation levels/heat loss.
*I’m assuming you don’t have a buffer/low loss header and UFH manifold doesn’t have pump/mixer - if you do then this may require more to get the best out of the system!
Thank you for the reply. The plan is to run the ASHP 24/7 and use the compensation curve to maximum effect.
The bungalow is highly insulated, all UFH, with a buffer tank, no pump/mixer.
Whilst I am still experimenting with the system, is there and technical issue with me holding open the actuator value (given that they have a wax ellement in them?
Just unscrew the actuators like I said (maybe mark them up first). If you have a buffer, then there will be a secondary pump, which will be enabled by the UFH wiring centre when at least one zone is calling.
Ideally, if possible remove the buffer and secondary pump and feed directly from heat pump and don’t use zone controls/stats apart from bedrooms etc.
Yes indeed, it’s just the actuator head that screws (the silver knurled ring at the bottom) on to the manifold zone valve, just like a TRV - no wellies required…hopefully
Yep. As Tony already advised, the actuator head just emulates the sensor head on a TRV and pushes down on a plunger in the manifold. Removing the actuator head won’t result in any water leaks.
My own experience is that I needed to retain per-zone control of the UFH - though I’m suspect I’m firmly in the ‘high solar gains’ category. On cold-but-bright days the south side of my house gets many kW of passive solar gain and with the UFH purely under Weather Compensation control the south-facing rooms would get uncomfortably hot - and stay hot since there’s a lot of thermal mass and very good insulation. I therefore found I needed to use the per-zone actuators to dial-back the UFH heating on the south side of the house when there’s lots of passive solar gain.
[In my case, rather than using room thermostats, I have temperature probes inserted in tubes embedded in the floor slab and I limit the floor slabs to 25C, so that if a UFH zone is being heated by the sun it gets a reduced water flow, tending to direct the heat towards the north side of the house instead. Using a ‘slab’ thermostat makes for a slightly more responsive control loop than using a room thermostat, but they’re doing the same job. I then have one indoor temperature sensor which feeds into the WC algorithm, reducing the flow temperature if the whole house gets too warm.]
Simple is best though, and if your UFH loops are correctly sized and you don’t get enough passive solar gain to make the south-side significantly warmer than the north-side you are better off without the complication of per-zone control. It depends on whether you have lots of south- or west-facing glazing - and how you use the rooms on the north and south of your bungalow. But don’t be astonished if you find the room temperatures aren’t as consistent as you’d like - especially when it’s below freezing but sunny.
I’d say see how it goes during the rest of the heating season, with all the actuators ‘clipped’ or removed from the manifold. You can always reinstate the actuators on any rooms which tend to overheat. Even if you need to retain some of the actuators, you might be able to retire one of the two heatmiser control units.
Yes the bungalow is south facing with significant glass, so today, lots of sun the family room was at 24C whilst the bedrooms on the north side were just 20/20.5C. Didn’t need any heating today. I do have a air conditioning unit (hot/cold/just air. So I blow air from the family room down to the bedrooms. Works quite well.
The family room over heating is going to be a problem with the heating on. So as we have not had a winter season here, just going to have manage the situation and find the best solution.
A temperature probe in the floor would have been a good idea.
Ah, so broadly similar to my place then - in terms of passive solar gain (and its differential impact on room temperatures). I also had the south-facing rooms go 4C higher than the north- and east-facing rooms today (with no heating on) though things are starting to even out now the sun has set.
It’s good you’ve got the ability to blow some air to help to move the heat around a bit.
As long as there’s some flow through a UFH zone, a temperature sensor strapped to the Return pipe for that zone is a good proxy for the Slab temperature, and much easier to retro-fit
