Fitting TRVs

AndyBill · 27 Jun 2007

Hi,
my mother in law wants TRVs fitted to her old radiators,
does the system have to be drained down?
is this a very easy job to do?

by the way im not a plumber !

bobthebender · 27 Jun 2007

AndyBill said:
Hi,
my mother in law wants TRVs fitted to her old radiators,
does the system have to be drained down?
is this a very easy job to do?

by the way im not a plumber !

You could freeze each pipe

Or drain system

JohnD · 27 Jun 2007

It's summer time, so it will be much less trouble to drain the whole sys and fit TRVs all round in one go. Do not fit a TRV in the rom with the room stst in it (nor in the hall if it is usually cold) Make sure the boiler is turned off while drained. If there is an immersion heater then the hot taps will still work.

Give it a chemical clean and re-inhibit while you're at it. If you run X400 for a couple of weeks (running the circulating pump even with the boiler cold) it will loosen a lot of old rubbish.

It is not very difficult but you will need a key to unscrew the old tails if you find they do not fit the new valves. Also replace any of the lockshield valves that seem old, stiff or leaky (lockshields are very cheap). Use a Dremel or similar, or a mini-hacksaw, if you have to take off any old olives.

Get al your tools, PTFE tape, boss white etc ready before you start. Fit rad valves with drain-off downstairs if the syst is short of drain-offs.

AndyBill · 28 Jun 2007

thanks john,
do you drain the system from a rad or from a drain near the boiler?
she lives in a bungalow

Diyisfun · 28 Jun 2007

If you are lucky you might find a drain off point, if not do it from a radiator.

gas4you · 28 Jun 2007

From the lowest point, but if the rads are on drops you will have to drain all the rads individually.

AndyBill · 28 Jun 2007

oh and shes got a back boiler ! does that make any difference to anything?

gas4you · 28 Jun 2007

You don't need to drain the back boiler if they are all on drops, but it would help eliminate a possible air lock when re-filling system if you did.

JohnD · 28 Jun 2007

if it has a back boiler it is all probably very old and rusty, so the chemical clean and inhibit is important. Bale out the Feed & Expansion tank and sponge out remaining sludge before you drain. If the F&E does not already have a lid, buy or make one.

If it is difficult to drain or has no/few drain-offs, fit a few of these (especially on the rads nearest external doors that you can run a hose through.

They only cost a few pounds from Screwfies and will replace the lockshield.

p.s. if any of the rad pipes come up through a concrete floor, it is much more difficult as they have no play on them, and rad valves that are not the same size and shape as your old ones are tricky to fit

diynot

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Fitting TRVs

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