Underfloor heating weather compensator help

[Cameron]

Hi all

Planning to install a large wet underfloor heating system in my hous

140m2

I want the system to be hardwired, ie no fancy control boxes, fanc electronics, etc (this way I can always fault find + Im tight)

I would like to include a crude 'weather compensator ' to control th water tempurature.see

Outside tempurature 5oC - water temp 40oC Outside tempurature 0oC - water temp 45oC Outside tempurature -5oC - water temp 50oC

I can currently only think of one way of doing this.

1) Install 3 mixing valves 3 motorised valves and 3 outsid thermostats The valves could be cascaded and depending on the outside tempurature could select a heat setting. - Downside its crude and would b expensive.

Any better ideas.

regards

Camero

-- Cameron

[Onetap]

Yes. Electronic controller. One 3-port control valve, infinitely variable flow temperature.

Weather compensations controls the heating flow temperature according to the outside air temperature. One of the pit-falls for the unwary is that simple weather compensation, whilst an advantage when the heating & building is up to temperature, can't respond to the indoor temperatures. On start-up the building is cold, but the heating is still run at a reduced temperature because the heating doesn't recognize this.

[Doctor Drivel]

Most have room temperature influence.

[Doctor Drivel]

Why 3 of everything? 3 zones?

Have one flow pipe from the boiler or thermal store. Have the compensator control this to give the right temp. Off the flow have a manifold., From this to the UFH zones. On the return the same, a manifold and the returns from the UFH zones

Each zone may have solenoid valves to switch off or on to local room temp, floor temp or whatever. The pump should be smart pump like a Wilo Smart or Grundfos Alpha, so when the zones are off the pump stops (well slows up). If the boiler requires flow then a by-pass valve needs to be fitted and no smart pump. Have pipe stat on the flow set to 60C so that over hot water is not sent into the zones.

[Onetap]

Yes, Drivel, some do. But what the OP wrote was this;

Which clearly would have no inside sensor. Got it? Fool.

[Doctor Drivel]

Danfoss Randall do a weather compensator for £160. I saw a few for sale on Ebay for £40 - now sold.

[Doctor Drivel]

Crudest and cheapest is three outside stats and three pipe stats on the flow. Cascade three outside stats.

Outside temperature less than - 5C: ouside stat No 1 swiches in pipe stat set to 50C. Pipe stat switches boiler Temp rises above -5C outside stat No. 1 breaks on temp rise, switches over line to outside stat No. 2 set to 0C, pipes stat set to 50C de-energised. Outside stat No 2 energises pipe stat set to 45C Pipe stat switches boiler Temp rises above -0C outside stat No. 2 breaks on temp rise, switches over line to outside stat No. 3 set to 5C, pipes stat set to 45C de-energised. Outside stat No 2 energises pipe stat set to 40C

Have a high limit stat to cut out the boiler if it gets above flow temp of

55C to 60C.

Temp ranges: below -5C 50C flow between -5C and 0C 45C flow between 0C and 5C 40C flow

[The Natural Philosopher]

This is good.

This is not good.

Most of the electronics is simple. I have not head of electrically adjusted temp regulators.

I just run mine flat out, and use a thermostat to cut the thing off when the rooms are warm enough. A slightly smarter thermostat would be better as I get about 1 degree overshoot.

The wiring is quite large, but simple. In essence apart from a relay to wire or the boiler so that turning the boiler on for e.g. hot water doesn.t fire the auxiliary UFH circulation pump, it is essentially no worse than a normal CGH circuit with a couole of stat controlled TRV's on sub zones.

I don't see why you would want to modulate UFH water temp.

[Doctor Drivel]

See my other post on how to so it. Better buying cheap waeether compensator as th cost may be about the same.

You run plastic UFH pipes at 80C? My God!!!

You don't know much about these things do you?