Replace TRV

[Joet]

Well what started as an easy job is turning out to be the opposite.

Working in a customers house in a bedroom plastering the room etc so taken the rad off and she's mentioned new TRV so thought yep easy enough, done a few now.

So I was going to shut the water supply off to the combi boiler and then drain the system via a drain valve downstairs. But I can't see how to shut the water supply off (potterten profile 60e) and there are no drain valves on the system!

Any ideas how I stop the water supply to the boiler? I now know where the stop cock is.

Could a make an adapter to fit a hose so I can drain the system from upstairs or do I need to do it downstairs?

 

[Armo74]

The supply should already be shut off via the filling loop but you need to find it to top it back up and make sure it isnt on.
Try under the kitchen sink.
Drain bedroom rad from downstairs you only need to do a partial drain down.
Find the easiest rad to remove and there are various ways of attaching a hosepipe to the valve.
Don't forget to add inhibitor before you top up.

 

[Joet]

I couldn't find the stop cock when I was there and customer didn't know herself, but she now knows.

So if I turn boiler off via fused spur then shut of mains water in to the house, this will work?

Then drain the system

 

[Armo74]

You still need to top the pressure back up

 

[Joet]

Sorry I don't understand, at the minute don't I just need to stop the supply to the system then drain it right?

 

[Armo74]

Don't think this is a combi as you said.

 

[Joet]

There is an immersion heater and what I thought was a combi. In the loft there is a big and small cold water tank.

 

[Joet]

Ok maybe it isn't a combi. What would the process be so I can shut the water off to change the TRV?

 

[Armo74]

Go in the loft and isolate the cold supply to the smallest tank of the 2 if you can.
This will cause minor disruption.
Any motorised valves will have to be put in the manual position.
Partial drain down from downstairs rad.
Replace TRV. Top up with inhibitor
reinstate water supply and top the system up.
Vent all rads and other vent points.
You can bung the cold feed and vent pipes but not advisable if you are unsure.

 

[Joet]

Didn't see a shut off for the small tank but stopping the ball cock from dropping would be the same? There was some string as if it had been done before.

So either shut supply to small tank or support ball cock then drain the system off from downstairs? Does it have to be a particular rad?

 

[Armo74]

Not a favourite method of mine but yes you can tie the ballcock up.
A rad on a floor surface that can easily be cleaned is preferred.

 

[Joet]

Hmm thinking of hiring a freezing machine - think this might be safer option. Any experience with them?

 

[Armo74]

I wouldn't bother with that the safest way for you is a drain down.
The quickest and least disruptive way if you know what your doing is plugging the cold feed and vent pipe to create a vacuum in the pipe work this way you could change all of the valves one at a time without the need to drain the system.
Or you could do it live