Boiler stopped after replacing radiator valves air!?

[Geminineil]

Sorry for adding this to another thread.. but it is no longer about drippoing radiator but about central heating now not working... and with Christmas Eve tomorrow...

Can anyone help?
Having replaced an old radiator thermostatic valve using the 'bung method' I thought I would have a go at doing another two tonight... I accidently left one of the valves open one end... and also am not now sure whether you should do two at once using this... bottom line is,.. gas Netaheat boiler ran briefly... lots of knocking in pipes.. ie air... and now the boiler will not run for more than 10 seconds or more.. I can hear the pump 'beavering' away.. (or rather whining..) but only the hot water radiator in the upstairs bathroom is getting fed with hot water... how is the best way to fix it? (and yes I have tried to get a plumber around in the first place) help (please)?!

 

[WHPES]

Make sure the tank is full and that the ballcock is not stuck.

Excuse me if I am asking the obvious but are you sure the tank you bunged was the F&E tank and that the heating system is not sealed? Are there two tanks in the loft?

Bleed each of the radiators and any other bleed points such as the top of the DHW coil. Bleed the pump also (the big shiny screw in the centre).

 

[Geminineil]

Hi WHPES,

Thanks for your answer...

The attic where I live it has been panelled up.. I have removed one 'inspection hatch' about 3 days ago in the attic.. and a small water tank was there... I would say about 1 foot deep, x 1 foot width and 18 inches length... ... and replaced one valve in a groundfloor shower room.. .. and apart from it dripping all seemed to have gone ok... when I removed the old valve about a cup or two of water came out... I am no expert and don't know if I have a sealed system or not... The local plumbers merchants suggested that the upper most radiator in the house would have a 'ball type' object on it.. with a prssure guage... and I cannot see that... how do I know if I have a sealed system? My guess is that there is probably another cold water tank somewhere in the attic.. but I don't know where... ps... having restarted the system, and bled several radiators.. including the upper most one... things now seem to be working again.... pps. The small tank that I 'bunged' certainly had a bit of a filling as I could hear it...

 

[WHPES]

If you have the small tank in the loft then this is the one. There will also be a larger tank elsewhere.

Sounds like there is air in your system. I presume you have a copper cylinder. bleed your radiators and look for any bleed points elsewhere.

If you lost a lot of water out of your system you will need to add more inhibitor to prevent your radiators from rusting.

Don't try and bleed anything with the pump running - you can end up dragging more air in if you do that.

 

[Geminineil]

Thanks for the tips. where do I add the inhibitor? into the small tank?

 

[WHPES]

Yes, but you need to empty the tank and drain the system, add it to the small tank and let the water back in, bleed everything again.

Usual inhibitor is Fernox F1, Fernox MB1 or Sentinel X100

 

[Bernie2]

Hmm!

Potterton Neataheats are pretty old, heat only boilers and have some foibles, that I remember. One of them is the cold feed sometimes get blocked. My guess going by what you say is that you have got air down the cold feed probably.

It can be a job and a half to get it out.

The size tank sounds about right though.

Fill the tank with water up to its usual level, then if the air will not move.

Connect a hose from the cold main and push it down the cold feed and turn on, sealing around the tank connector with your hand. The water should come out the vent when the system is full.

By doing that you prove two things. The boiler cold feed is clear and the vent is free flow. Those are two important safety features. Anyway after that remove air from rads and let system turn over cold. Just switch boiler stat down to lowest setting. Remove any air from rads again. Check air in pump if you can.

After that make sure header tank is filling and the water level is about 50mm over outlet.

Should be okay after that if air is the only problem.

 

[Geminineil]

Thanks for the detailed suggestions Bernie... one more question.. I have two upstair radiators left to do... using the 'bung method' should I only do one at a time or is it safe to do one and then the next while I have the heatig off and'bunged'?

Thanks

Geminineil

 

[Bernie2]

Hi! Geminineil,

It shouldn't make any difference. If you refill one at a time.

But do it slowly, if you think you might get more air problems.

Some systems fill that quick the feed and expansion tank empties before the rad is full and you draw more air into the system through the tank outlet.

Good Fortune!

 

[WHPES]

If you're replacing standard valves with TRVs you MUST change your bypass valve to the automatic type.

Do everything in one session - less hassle in the long run.

Don't add any inhibitor to the system until you've finished or it's a waste of money if it runs out again.

 

[Geminineil]

I am replacing - what I think are Giocomini thermostatic valves... with COMAP Westherm ones.. and touch wood... the last ones I have done don't leak... 10 turns of PTFE tape.. (Wound the correct way this time) one of the worst parts is getting the old olive off ... have to change all of the fittings as the Giocomini old nuts are the wrong size (so to speak!)

 

[WHPES]

Have you checked your bypass valve (in a loop which comes from after the pump and links into the boiler return. In old systems this usually has a gate valve in it which you need to replace with an automatic valve).

 

[Geminineil]

Hi WHPES - is this even if I am replacing GIocomini TRVs with COMAP TRVs?

 

[stevetheplumber]

Hi WHPES - is this even if I am replacing GIocomini TRVs with COMAP TRVs?

noy necessary realy

 

[secret squirrel]

Whenever I have nuts the wrong size I......... Anyway....

If your struggling getting the olives off then I'd highly recommend an olive puller, some plumbers will cut them but I'm too nervous for that and too impatient I'll end up damaging the copper tube.

 

[Geminineil]

Have finished the final two radiators... YAY! Thanks to all that have offered help - it has been much needed support... Have a great Christmas....

for what it is worth... and maybe for novices.. and possibly for real plumbers to advise different - this seems to have worked...
1. Turn off central heating and wait for pump to stop
2. Place bungs in Expansion tank - Cold feed pipe first then Expansion Pipe
3. Shut off end of radiator that is not being changed
4. Loosen large nut on end of radiator (Union I think?) and using plastic lunchbox type plastic box... empty radiator contents into a nearby bucket - open rad bleeder to help water run out quicker
5. Screw the Union/Rad fitting back on a little... and then undo the old TRV nut connecting to pipe... (if you don't do this then the pipe twists)
6. Either undo the old TRV (I was cautious about doing this until I had loosened the UNION fitting in case of a lot of water coming out.. and it didnt)
7. Remove old Union and old TRV.....
8. For my sins I wound PTFE tape around the new radiator male fitting 10 times.. and that seems to work... (looking into the end of the male fitting - wind clockwise)
9. The guy at the plumbers merchant told me to not put ptfe tape around the olive fittings on the TRV.... I did on a couple of joints as they leaked a little no matter how tight... (not sure if that is necessary or not)
10. connect back up... remove bungs in expansion tank in reverse order... then BEFORE turning heating on... bleed radiators by first turning on the end not touched... and open rad bleed screw until air has come out...
11. On a couple of radiators I had to also undo the opposite end.. as there was not enough pipe work to work with.... on the male end on refitting I put some ptfe tape..
12. One of the worst things is getting the old style dolly off.. a couple just fell off.. and a couple took about 30 minutes to get off... I have just completed my final two rads in about 1 1/2 hours...

When all is done.. fingers crossed for no leaks and turn the heating back on... for my sins.. I also went around again bleeding...

Bottom line is I am no expert and don't profess to be... but in the absence of a plumber this week have changed 5 old style TRV thermostatic valves) I should add that the tool that the plumbers merchant provide to remove old union fitting is only supplied with about a 5 inch rod... and it needs to be 4-5 times this to get enough leverage to undo the union... a long screwdriver worked for me... I should also add that rust inhibitor will need adding to the system and maybe I should have done that on my last assigment.. but on Christmas Eve and not a plumbers merchant in sight open.. that will have to wait...
if whoever moderates the forum wishes to remove this post as it isn't the way things should be done.. then no problem... I have really appreciated all of the comments given.. next time I may well try to find a plumber a little sooner to save me the hassle.. but job done for about £70... Happy Christmas and New Year to you all!

 

[WHPES]

Now you've finished you can add the inhibitor.