Under floor heating wiring problem

[cjohnsonuk]

I'm not sure who was to blame on this one but when we had the UFH put in in our conservatory nothing was mentioned about the need for a wire to control the boiler and it didn't occur to me at the time.

We have just finished decorating and found that we need this extra wire from the output of the zone valve to turn the boiler on.

So we have in the conservatory the thermostat/timer, manifold, pump and separate direct feed and return from a T under the boiler, the other end of the T going to the radiators in the rest of the house so the two circuits are separate.

The boiler is one floor up on the back wall of the garage on the other side of the house. Tiled floors and newly plastered ceilings and a block wall separate the two.

The boiler is an Alpha CD50 fitted with a wireless easi stat which controls the temperature and timing of the boiler.

The problem is for those that have not yet worked it out that the easistat time and the timer in the conservatory won't be set with the same timings. We want the conservatory heating to come on early to warm the floor but the radiators to come on later to stop us roasting in our beds. However the timer in the conservatory has no way of signalling the boiler to start so it will be pumping round cold water!

I can't work out a way to get the stat in the conservatory to control the boiler at the same time as the existing easy stat controls the rest of the house.

I know I will need another zone valve and a bypass valve to zone off the rads for when just the UFH is on but can anyone suggest a way of getting both timer/thermostats to work together or a combination of new timers/thermostats that doesn't require redecorating?

I've called the UFH people, our boiler fitter and the people at Alpha who have all been helpfull but have always ended up with a compromised solution, usually losing the room thermostat function.

We want to avoid redecorating as, after 12 months of living with the builders in we're finally getting our house back!

The only working solution I've been able to find is to fit both zone valves in the garage with the boiler with a two channel timer and to forget about the thermostat function unless we can get remote wireless thermostats. The easystat will become redundant in this case which isn't ideal as it was expensive!

I'm not sure if an additional single channel timer will work in parallel to the Easystat to save a bit of money and to allow us to continue to use the easistat which is convenient.

All the radiators exept a towel rail in the bathroom and a radiator in the hall have thermostatic valves, as does the UFH.

If all the radiators were fitted with thermostatic valves am I right in thinking that the boiler will switch itself off when the returning water is still hot?

Any suggestions welcome.

ChrisJ Sheffield

[David Hansen]

On 30 Oct 2006 15:22:12 -0800 someone who may be " [e-mail]" wrote this:-

These gadgets are presumably fed with electricity from somewhere. How is this run? If it is done sensibly in some sort of conduit can you fiddle the existing cable out and replace it with one with more cores? Three core and earth cable is not that much bigger than two core and earth. If the cable is plastered into the wall then you may end up pulling it out, replace with a cable not plastered into the wall and redecorating that bit.

Provided there is a suitable bypass, which the towel rail may be. However, the boiler will then short cycle on and off which is not ideal.

[cjohnsonuk]

for the Domestic hot water, not sure if it does the same for the heating circuit.

The wiring is not in conduit, just threaded through holes in the ceiling, floor and stud walls so there is very little chance of getting a different wire through, especially as the power for the manifold pump is on a fused spur.... ;0)

But do I need a thermostat? If I've set all my radiators thermostatic valves correctly and use timers to set the boiler to come on when we are in the house /want teh UFH on what extra benefit is there to having an additional thermostat on the thermostat timer? Is it just to stop the boiler firing up in teh first place to see if the water coming back is warm when the house is already warm?

Chris

[David Hansen]

On 31 Oct 2006 15:13:06 -0800 someone who may be " [e-mail]" wrote this:-

You might be able to draw a three core and earth through using the old two core and earth. I haven't seen the installation, but I suspect it would be possible.

I'm not sure what the relevance of this is.

My answer to this question remains the same as it was last time.

[cjohnsonuk]

between the boiler in the garage and the thermostat in the conservatory. The power for the UFH manifold pump comes from a fused spur off the sockets ring. The only other wire is between the thermostat on the wall of the conservatory and the cupboard in the conservatory where the manifold has been installed. All that links the boiler and the manifold is pipes!

What I need (I think) is to be able to ge a signal from the thermostat in the conservatory to the zone valve under the boiler to open teh valve which will in turn signal the boiler to fire up.

Any ideas?

ChrisJ