Wiring up underfloor heating

2 Aug 2008
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United Kingdom

Currently have an extension and renovation project ongoing. The plan is to install wet underfloor heating in the new kitchen and utility room which will run of the existing central heating system (s-plan) as a third zone. (zone 1 Hot water, zone 2, existing rads). Extension too large to use a "one-room" u/f pack so plumber is supplying manifold with pump, control valves etc.

Question .... can the underfloor circulating pump simply be wired in parallel with the zone valve for this part of the system, or must something clever be put in to ensure that u/f pump over runs for a given period after the stat stops calling for heat.

That is ... is an expensive u/f specific wiring centre required or can the existing (simple set of terminal blocks) be reused

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All the instructions/wiring come in the ufh pack afa I have ever seen. A programmable room thermostat often suits.
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You need a relay to control UFH pump.

Perhaps my glass of 15% wine is dulling my thought processes but I dont see why a relay should be required.

However, due to the long thermal inertia of UFH a better form of control than a simple room stat is preferable.

True, optimising programmable ones are better - still only about £50, and you still have to set them to come on early!
As per normal S-Plan I had planned to put a stat and a programmer or programmable stat in series with zone valve power terminals and use the other set of terminals on the valve to give a volt free swich to the boiler. Question was do I simply wire the UHF pump in parallel with the zone valve power terminals so UFH pump runs whenever stat calls for heat. Answer appears to be yes.


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