heating zones, TRV's and bypass rads

[Hazelb]

We are changing our heating system from a conventional system (rads and room stat) to one fitted with TRV's.
I know one rad needs to be left without a TRV control.
The system will be controleed by a time clock.
Is it usual to set the system up so that it continually runs ( through the bypass rad iif/when all the TRV's are closed) or is it usuall to fit a room stat somewhere as well, to turn the pump/heating off?

An extension we had built has had a seperate heating zone put in it.
The zone for the extension has 3 rads fitted with TRV's and a radiator on a bypass circuit. It also runs on its own timer.
The rest of the house has conventional rads ( no TRV's) and is controlled by a room stat. is on a seperate timmer and heating zone. It has no TRV's and is swithced by a room stat.

When the extension timeclock is on, the heating circulates/heats continually. Is this an efficient way of runniing the heating or should a room stat be fitted as well?

 

[plummit]

I do believe, but am never sure, that a room stat is still required.Personally, i would put the room stat in the most used room in the house, and leave out the trv's in that room. Having said that the room stat in my house is in the kitchen, there is a trv on the rad there, but hey fitted the system myself !. Personally, i think trv's, are a bit of a gimmick, have them on most rads in this house and have never altered them, also heard of a few other plumbers, that they dont bother either. But i guess you now have to fit them.

 

[blahblah]

Sounds like a dogs dinner.
Each zone should have programmer and roomstat (or better- programmable roomstat). If your extension is one room it should have a roomstat and not trvs. If more than one room then trvs in the rooms where the stat isnt. Fit an auto bypass in you system and you can do away with 'bypas rads'.
The object of the evercise is NOT to have a system that continually runs when the clock is 'on' but one which shuts down the boiler when heat requirements are met. That can't happen with index rad and no roomstat, the boiler will keep cycling.

 

[PEDANTICVINDICTIVEMAN]

You need to look up the Part L building regs to do it all to correct spec.

 

[ChrisR]

Just to be confuddling that says you only have to have trv's in bedrooms! I reckon 90% of the trv's I come across are full open.
Use room stats -agree with blah.

 

[breezer]

my 2 p worth

here i sit in my "office" its too hot, i turn trv down (it does work) problem, if it gets v cold outside, its too cold in here, turn up trv, although they are good, i think they are a pain

 

[ChrisR]

I don't follow - why is the room temp affected by the outside temp if your trv is working?

 

[breezer]

i have 2 outside walls and a window (slightly open to prevent condensation)

heating is "goverened" by room stat downstairs, havent changed irs setting in ages (or boiler) but it gets v hot in here some days when it rains outside, so i figure it must be cold outside. perhaps this trv is none to acurate (but i am not going to "touch it", its an old looking one)

 

[ChrisR]

Bet you 10p it's fully open!

 

[breezer]

it was, (3 clicks down, its dark under the desk) but then it will get too cold

 

[Witzend]

We've got TRV's. We had them at our old house 20 yrs ago and I thought we'd have them in our current house as we've had our heating revamped. I now remember that they were rubbish and still are. You can easily turn the knob down on your radiator if the room is too hot. TRV's vary enormously in what they think is hot and I'm thinking of taking them off. It shuts off too early for my liking leaving a room too cool! We have a room thermostat in the hall but at the moment it's set to max as some of our rads aren't getting hot enough. There's a TRV also on the rad in the hall!!!

 

[kevplumb]

revamped or botched

 

[blahblah]

A quality trv properly positioned on a well designed system works just fine in my experience. Don't blame the little fella for the system being kwap.

 

[kevplumb]

shuts off too early for my liking leaving a room too cool! We have a room thermostat in the hall but at the moment it's set to max as some of our rads aren't getting hot enough. There's a TRV also on the rad in the hall!!!

stat and a trv ????

 

[croydoncorgi]

We have a room thermostat in the hall but at the moment it's set to max as some of our rads aren't getting hot enough. There's a TRV also on the rad in the hall!!!

Oh dear!
With a TRV presumably turned up high AND a wall stat in the same area, you are BOUND to have other rads not working! To make the OTHER radiators HOTTER you must TURN DOWN the TRV on the rad near the thermostat. That will ensure that the boiler / pump keep going and heat the rest of the rads.