I'm building a straw bale house that I hope to certify as a Passivhaus, so it has very low heating demand. We're just finishing first fix and I'm putting the final bits of wiring in before we close up the walls and ceiling, so I really do need to make my mind up about heating now! Or at least make my mind up about initial heating and any wiring I might want to be able to change in the future.
It's an all-electric house, so my basic strategy is to scatter electric heaters around, although I do have a thermal store with some spare tappings so I could add a fan-assisted radiator in the hall later if it seems like a good idea. The house is designed as a Passivhaus and our max heat load as indicated by PHPP is around 1.5 kW.
I've put power wiring to fused connection units in various places:
* each bathroom/ensuite
* living room
* plant room to connect a post-heater in the MVHR
* downstairs hall for a fan-assisted convection heater
The ones in the wet rooms and the living room are intended for relatively low-powered infrared heaters to provide comfort warmth if needed. They could also be turned on overnight to take advantage of E7 tariff. The MVHR could accept up to a 1.5 kW post heater; the hall could use up to a 3 kW fan heater. Obviously, I could also later add additional small heaters via 13A sockets anywhere.
Being well-insulated and probably moderate to high mass (straw bale and plaster, plus a concrete slab under the floors) I expect it will have a long time constant. There'll probably be somebody at home most of the time as well. So I'm not too concerned about programmability and I plan to just try to keep it constantly warm. We should only need any heating for three or four months.
The question that is puzzling me now is what do I need to build in for heating control? Individual thermostats for the various rooms with heaters? Some kind of network? External sensors? Do the thermostats directly control the heaters or should I build in some 'brain'? And is everything connected together via mains wiring, bell wire, Cat 5, wi-fi or some other wireless system? And how do I do it all without spending much?
Since I'm posting here, I suppose it is obvious that I'm wondering whether I can sensibly do all this using an Open Energy Monitor system, and what would be involved if I can? How much can I buy off the shelf and how much would I have to build and/or develop?
Re: control system for a new house
I have a follow-on question already! By browsing the site, I can see most of the parts of a possible system. The part I'm left wondering about is controlling the heaters. I need some sort of power relay, which would need to be located close to each heater. Ideally, the relays would be controlled wirelessly by the monitor system and/or manual switches. Are there suitable wireless relays?
Re: control system for a new house
First, put in plenty of plastic pipes through which you can run cables later, with little or no disruption to the decoration.
The follow-up question first: Robin Emley (calypso_rae or Mk2PVRouter.co.uk) offers a wireless remote switch using a triac - it's an emonTx and the triac output stage from the PV diverter designs.
But if you're still at 'first fix', why not leave your ring main for all the 'usual' appliances and take all the power cabling for the items you want to control automatically/remotely back to a central point, then you won't need to worry about wireless, interference or anything else. And it will probably be cheaper too. If you have a central 'brain', you can easily have a lot more intelligence and take weather (temperature, wind, insolation?) into account as well as internal temperatures.
Re: control system for a new house
"First, put in plenty of plastic pipes through which you can run cables later, with little or no disruption to the decoration."
Thanks for your comments. I thought about putting in extra ducting, but I have enough trouble knowing where to run e.g TV points, let alone where to run ducting for some purpose that I don't [yet] know!
"The follow-up question first: Robin Emley (calypso_rae or Mk2PVRouter.co.uk) offers a wireless remote switch using a triac - it's an emonTx and the triac output stage from the PV diverter designs."
Ah, excellent. I'll probably end up with his diverter for my PV panels anyway, so it will be sensible to use the same building blocks.
"But if you're still at 'first fix', why not leave your ring main for all the 'usual' appliances and take all the power cabling for the items you want to control automatically/remotely back to a central point, then you won't need to worry about wireless, interference or anything else. And it will probably be cheaper too. If you have a central 'brain', you can easily have a lot more intelligence and take weather (temperature, wind, insolation?) into account as well as internal temperatures."
The heater power isn't on the main rings. The MVHR post heater and the hall fan heater have their own radials. The three wetrooms and the living room are on a private ring; I have (had?) ideas of switching power to the ring on an E7 timeswitch. But due to the layout of the house, I could reconfigure that ring to be four separate radials by the use of one extra length of wire, I think. That does sound like it's worth doing. Thanks very much for the idea.
The consumer unit, solar PV, thermal store, router and the hoped-for 'heating brain' will all be together in a cupboard in the utility room. So if I rewire as you suggest, I'd just need remote temperature sensors and manual override switches local to the heaters.
I'm basically a software type, though I can do simple electrics and soldering etc. I need adult supervision for mains stuff, but my electrician is helpful.