Finally getting round to install thermostatic radiator valves to most of the radiators - not bothering with the hall or bathroom.
Ours is a conventional gravity system does anyone have recommendations as to the best thermo valves to buy. Does price make that much difference? as there are vast differences in costs of certain units.
Anyone any tips for fitting or point me in the direction of a step-by-step guide?
Which end of the radiator do they go? we have what I believe are called lockhead valves one end (that regulate the flow) and a valve with a kind screw-down tap the other end for if you want to turn the radiator off.
The "best" are supposedly Drayton TRV4's, but they are expensive.
I personally use Drayton RT212's throughout as there were some already in so they matched, and they're cheap enough to replace if necessary at Anyone any tips for fitting or point me in the direction of a
May not be entirely what you need, but you can get the idea:
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They generally go on the feed end, but if you get bi-directional ones (which the RT212's are), then it's not the end of the world if you put it on the wrong end as it will still perform fine.
I'm guessing you mean a vented system (small header tank).
A gravity system means no pump, and water circulates by convection between the boiler and radiators, and is characterised by large diameter pipes and usually large old cast iron radiators with inlet at top and outlet at bottom. I suspect TRV's would present too much flow resistance in this case.
As someone else said, the Invensys/Drayton TRV4 is usually regarded as the best.
Problems you can get with some cheap ones are leaking through the pin, pin jamming, and when the head wears out, no spares available so you have to drain down, remove and replace the whole valve.
_lockshield_
You still need the flow control, which is normally provided by the lockshield value. The Drayton TRV4 does actually have the ability to set flow control too, but you need a separate special tool to operate the flow control adjuster. Normally that's not done because a lockshield on the other end does it, and it's also useful to be able to isolate a radiator if necessary.
With regards to price, cheapest I found 7 years ago was to buy a box of 12 from an independant plumber's merchant, even though this was a few more than I needed. eBay may be worth checking nowadays.
The 'stat valve has a directional arrow on it to show which way the water must flow. If you don't know then turn off the radiator(s) when the system is cold, switch on the heating, then open each valve in turn and see which end of the radiator gets hot first. It does not necessarily follow that the lock-shield valve is on the radiator outlet even if it ought to be!
The specific idea of the lock-shield valve by the way is to balance flow so that radiators closest to the heat source do not get seriously over hot at the expense of those at the other end of the system which may only get warm.
It has always struck me as odd that you if put a 'stat valve on the rad inlet it is upright and thus closer to the radiator. I put mine on the outlet so they are horizontal and they seem to work well.
In practice most are now bi-directional and have a double ended arrow to indicate this.
If you are clumsy or have kids then vertical is the way to go, it lessens the risk of damage, but I agree that horizontal seems a better idea for temperature control with horizontal and on the cooler return side being the ideal. That said, TRVs are a pretty coarse level of control of room temperature.
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