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rolyberkin

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I have a heating system which I need to buy a controller and thermostats for, will have 2 x two port valves, 1 zone will be rads and the other a single underfloor zone with independent pump, and hot water, was thinking about a Heatmiser UH4 with 2 wired thermostats? Any other or better suggestions for controls please?
 
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What is the heat source, the problem with any zone system using standard motorised valves is the valve is open or closed, it does not modulate the flow, but modern boilers modulate the output, so a zone for CH and a zone for DHW is so the CH can be isolated in the summer.

But with a zone for two CH devices what needs considering is how these will impact on the efficiency of the boiler, with electric or oil often the boiler is only off/on so zone valves no problem, but with gas the boilers normally modulate either with the ebus or return hot water, so the programmer can work the zone valve, but not the thermostat.

There are some really complex building management systems, but with domestic less options, but I would look at basic concept first, you want a single boiler to control many rooms independently. If each room had an on/off control then as the room count increases the combined return water becomes an average, and using TRV to control each room they modulate anyway, so why use a zone valve? Or maybe better put is why use a wall thermostat.

Well in an ideal world if any TRV head reported if target is above current then boiler would run, however not an ideal world, the problem is as summer approaches the boiler start to cycle, and unless stopped would cycle all summer, so we need a wall thermostat to stop the boiler from cycling all summer, so the age old idea was wall thermostat in a ground floor room with no outside doors normally kept cool and no alternative heating, in my experience rather a rare room.

So we get systems like tado and EvoHome which can monitor many rooms and control the boiler either on/off or OpenTherm to ebus.

So in the main what we are trying to do is get same results but spend less.

So underfloor heating is slow to respond and useless at controlling the heat to the room, so simple zone valve connected to a programmer, and do all control with the radiators and their TRV heads, so no zone valve on supply to radiators, you want some thing to turn off boiler so select a few key rooms to have wifi heads which link to a wall thermostat to switch off boiler when no longer required.

In my case 5 rooms have eQ-3 heads £15 each to limit the temperature of those rooms, they will not cause the boiler to fire up, but those rooms will likely be needing less heating than the control rooms so should look after them selves, and 3 rooms have wifi TRV heads which connect to the wall thermostat, which in turn tells boiler when to run, I have oil which has very limited modulation so on/off control is good enough.

As I see it as installer EvoHome is safe bet, you know it will work, but a system like mine your open to be called back saying rooms are cold, so as installer is it worth it? As the user what ever is fitted by the user the user clearly understands so will not mess it up. But an installer can set every lock shield valve spot on and every TRV head spot on then the user feels he/she is cold so alters them all. Then blames you that it no longer works correct.

I got stand alone programmable TRV heads for £15 each with blue tooth, but wifi heads cost £40 each so £25 per room difference, but for installer the client pays that, so 8 rooms is £200 extra to have wifi instead of stand alone, and you will not be called back, so is it worth using cheap options?

I was dead against Hive, I thought it was a stupid system as it did not have OpenTherm, or any linked TRV heads, but last year they released their own TRV head which has a link back to the wall thermostat with call for heat system, on paper it looks good.

This is the problem with all of the systems, new things are released so what was a poor system becomes very good, and IFTTT has all sorts of ways to control being added to every week.

I am not saying how to do it, but I hope giving food for thought.
 
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