SHIVER ME TIMBERS (COLD RADS) / FLUSHING A CH SYSTEM

[ice cold rad man]

Hi

Just as winter descends (of course) 3 out of 4 upstairs radiators refuse to play ball.

All of the downstairs rads (there are 4) work fine.

I have viewed several other postings to try and glean some info, and tried switching off all the downstairs rads, and all the upstairs except for one of the faulty ones, but no joy.

Here's what we have upstairs:
-----------------------------------

bathroom radiator works fine.

bedroom 1 - no hot water on inlet pipe to thermostat end.
to me, this sounds like a possible blockage in the pipe?

bedroom 2 - hot water is arriving at the thermostat end, but not getting past there into the radiator. I would suspect a fault valve. ?

bedroom 3 - no hot water on inlet pipe to thermostat end.
again, blockage?

Because of the symptoms above, common sense tells me that there's not much point bleeding the radiators as there's no hot water getting into them. Am I right to conclude this?

BIG question - is it worth draining/flushing the system?
If so, how much on average would it cost for a pro to do this?

Secondly, is flushing something that an amateur should/could attempt?
I am a keen DIYer, and keen to learn about plumbing, but I only know basics like brazing pipes and fitting taps etc. I have not touched CH.

Thanks for any help/advice you can give.

 

[oilman]

First turn off pump then bleed rads. There may be no water in them at all, though I doubt this is the case. Unless you check it you don't know. You might find some hot water gets into the radiators while bleeding.

Next, but should be first really, what sort of system do you have? If it's a sealed system it needs different treatment from an open vented system.

 

[etype]

Common problem at start of heating season is stuck TRVs. Take off TRV head. You will see a short pin. If you push it down it should bounce back up. If it doesn't it's stuck. You can try to free it - very gently- by pulling , but dont pull it right out. You may need to pull it up and push it back a few times to free it.

 

[ice cold rad man]

oilman

I have bled the offending radiators - all clear water, no air came out.
how do I tell what sort of system i've got (excuse me ignorance). the boiler vents outside via a pipe - does this help?



etype

who would have thunk it eh? all the pins were seemingly stuck, although an initial press down using the end of a pair of pliers made the pin move in each case, and then slowly rise back up. so i decided to just give each one a gentle tap with a hammer (onto the pliers still in place), and this made a difference to each pin. they then rose up much higher than they were originally.

however, it appears that only one out of the three is now working (at least that's some progress!).

now, one of the remaining two dysfunctional rads does not seem to be getting any hot water on the inlet pipe to the TRV. could there remain a blockage somewhere?

conversely, the other one *does* have hot water on the inlet to the TRV, but the rad is still cold.


MANY THANKS TO BOTH FOR YOUR HELP
THIS IS AN EXCELLENT WEBSITE

 

[Registered Gas Man]

An open vented system has a header (water storage) tank similar to that of the H/W tank in the loft or above the height of the boiler, you also have a tank seperate from the boiler for heating your H/W usually in an airing cupboard.

A sealed system has a pressure vessel (more often than not its
red) attached to the boiler or in the airing cupboard, this means you have to top up the water in the Boiler occasionally.

So which is it? 1 or 2

 

[oilman]

If the pipe goes straight outside, and you have a pressure gauge, you have a sealed system. If you are getting water out there is probably enough pressure in system. But check what it is.

Sorry for the overlap Registered Gas Man, I was just typing this when your post popped up.

 

[ice cold rad man]

Registered Gas Man

it's definitely open-vented then. there is a water storage tank in the loft, and there is a separate hot water cylinder tank next to the boiler. these are located in the back bedroom.


oilman

the pipe does go straight outside from the boiler, but there is no gauge.


still unsure about the problem with the remaining two TRVs. how can i check that the valve mechanism inside is operating as it should when the pin is pushed down and released?

does this mean cracking open the TRV joint (and draining the system prior?). i will attempt (within reason) anything within my capability to solve this problem, but would prefer the solution not to have "ballache" written all over it!


THANKS AGAIN FOR TAKING THE TIME TO ADD YOUR VALUABLE COMMENTS.

 

[oilman]

You could check theoperation of the valve, though I don't think it's necessary, by closing the lockshield valve counting the number of turns required, then pushing the pin down and opening the bleed valve. No water should come out. Release the pin and water should come out.