Conservatory heating - how to 'zone' extended CH radiator?

[Matt]

No they don't. There is nothing to stop a thermostat being located

*anywhere* where it will receive the appropriate amount of output from the heating system. Lots of thermostats are located in hallways with no TRV's on the rads and controlling to a much *lower* temp than the main living areas. As long as the rads are sized correctly, the thermal losses through the structure are not wildly different, the outer doors are not opened on a too regular basis and doors from an area with a higher desired temperature are usually kept closed then they function well.

[dennis]

Well he has already been told how to do it using zone valves. What i said was a cheap alternative. Its not wrong it is just different.

Yes he has.

[dennis]

No they don't. Say you put the stat in the hall and set it to 15C as the temperature you want in the hall. Then the system will not provide any heat until the outside temp drops well below 15C and the hall catches up. I.e. no room set to a higher temp will get any heat until the temperature has dropped well below what the owner actually wants. In fact if the outside sits at 16C the rest of the house will also sit at

16C and the heating will not turn on.

Now go and think about where the correct place to put a room stat is.

[dennis]

You could have done it better:-

Find somewhere to break into the flow from the boiler. Tee in two zone valves one to feed the original circuit. One to feed the conservatory.

Fit a bypass pipe between the flow and the return before the zone valves (very important on most systems!).

Wire the room stat to the one valve. Wire a new room stat to the valve for the conservatory.

Take a live feed to the end switches on the valves and wire the other terminals to boiler on.

Now don't forget that you need to be an certificating electrician to do it legally.

[<me9]

Currently the outside temparature has not exceeded 16C for several days, and has dropped much lower at night. The house has remained mostly above 21C with a low point of 18C overnight.

The difference is due to solar gain, and general occupancy of the house, good insulation, and not due to any deliberate heating.

[Set Square]

And crap!

When? The OP was "Army ". I can't find any more posts by him in this thread!

[dennis]

Yes. and how does that effect what I said?

[Matt]

A huge number of systems have the thermostat in the hallway, Its not the ideal place by a long way but if you site a thermostat in say the main living area and this has a separate heat source like a gas fire you can severely depress the temperature in the rest of the house.

One of the key factors in hallway siting is to get the radiator sized correctly. If that is done then the boiler will run until the thermostat is satisfied, if the radiator sizes are correct elsewhere in the house then their requirements will be met. Make the hallway super insulated, fit it with a radiator sized at 250% of the requirements, fit the thermostat 2 inches above the radiator and it will be a dogs dinner.

No one except you was ever advocating a 15 deg C thermostat setting, a more practical 18 or 20 deg C - just below the main occupancy rooms is required. The main rooms will still stick at 18 deg C forever and a day with no boiler firing because of the lack of thermostat call, BUT a thermostat sited in a main living area set to 23 deg C with additional heat sources present could conversely in extreme conditions leave a bedroom at 18 deg C below zero.

[dennis]

From your post

" Lots of thermostats are located in hallways with no TRV's on the rads and controlling to a much *lower* temp than the main living areas. "

So a much lower temp is well above 15C then.

That is why you may need more than one stat wired in parallel. Just like a frost stat is wired in parallel with the room stat.

Single room stat system are a bodge. They offer almost no control.

[Set Square]

Have you never heard of programmable stats - which can be programmed to work at different temperatures at different times *and* act as frost stats in their OFF state? No need for any parallel wiring if you use one of these.

And it is *never* appropriate to wire in stats in parallel - thus controlling the *same* thing - as a substitute for controlling *different* things, as in zones.

[dennis]

Two parallel stats with a timer (the old way of doing it). Yes I have four of them.

So its never appropriate to have a frost stat then.

I think you are confused.

[Set Square]

No, *you* are confused! If you use a programmable stat, you don't *need* a frost stat.

However, you *can* wire a room stat and a frost stat in parallel - that is ok because you want to control the *same* thing - namely the house heating - with both of them. When it's *not* ok is when you need to control two

*different* zones - as in the original question in this thread - when the stats need to be independent, each controlling their own valve.

I suspect that you're *trying* to confuse us by introducing the concept of a frost stat in parallel with a room stat in another attempt to justify your half-baked scheme for this poor bloke's conservatory. Sadly, it won't wash!

[dennis]

I'm not confused. I understand how they work and how to setup proper control systems. You keep changing your mind.

See you have changed it again.

Its heating not a washer. ;-)

Anyway you forget the obvious...

Like you state that he may want to heat the conservatory but not the rest of the house so requires a valve. However if he is using the conservatory he probably doesn't want the house cold does he.

You state that he may want to heat the house but not the conservatory. If so he is at home so he may be happy to turn the TRV knob.

I stated that to get the heating to run in the house and in the conservatory he would need two stats. This is true for any building with large differences in the construction and, hence, the heat loss.

I think you are confused.

Anyway I am bored so you can carry on if you want I am going to watch TV.

[Doctor Drivel]

Lord Hall, you don't know about these things.

[fred]

In article , Set Square writes

Indeed, but methinks you are now being well & truly trolled :-/.

[Matt]

"Doctor Drivel" wittered incorrectly:

[Set Square]

Your right - I'm opting out - this bloke dennis@home has *got* to be a mate of Dr Drivel - if not an alias! Life's too short to waste any more time refuting his ramblings.

[Lurch]

On Mon, 03 Oct 2005 19:54:29 GMT, fred scrawled:

Not from this angle he's not. ;)

[Matt]

I had my doubts before over him, but then again I suspect everyone (except me!)

[Doctor Drivel]

Lord Hall, stop making up people. You are Matt. No behave.