Refilling a rad after decorating but pressure already low

[FrankM45]

Hi, I've removed a rad for decorating a week ago and now refitting. Prior to draining and removing it, the system pressure gauge was just below green, midway between the lower two red segments.
I understand how to refill and bleed the air and that I will need to top up the pressure afterwards, but as the pressure was low before I drained the rad, should I increase the pressure BEFORE i attempt to refill the rad? I'm concerned that if the pressure is already low, when the rad refills the pressure may drop too far and cause problems?

hope this makes sense. Boiler is a worcester greenstar 30cdi

Any help or advice appreciated.

Thanks

F

 

[45yearsagasman]

Top the pressure up before bleeding the rad. During the process you may have to top up pressure again as venting the rad will cause pressure drop. Once rad is full, set the pressure at approx 1 bar cold. Make sure your boiler is OFF when doing this.

 

[FrankM45]

Hi Pete
many thanks for that advice - I've done this a few times but never on a combi/sealed system.

I saw this advice below in an old post - is it still valid would you say?
In particular, No 3 - do I only open the TRV to fill, then open the lockshield when rad is full, as per the guide below, or does it not matter?

1. Turn off Heating
2. Re-fit radiator
3. Open thermostat vlave.
4. Open Bleed key to allow radiator to fill slightly
5. Close Bleed key.
6. Open Fill Loop raise pressure to 1 Bar then close
7. Open Bleed key to relese additional air.
8. Open Lockshield valve
9. Switch on heating, bleed radiator as required
10. Re pressurise using fill loop as required.

Thanks again

F


Read more: //www.diynot.com/diy/threads/radiator-removal.40208/#ixzz4OBhplYlr

 

[45yearsagasman]

I would normally open both valves during the venting process but your way will be ok, because you didn't drain anymore of the system either method will be ok. Just make sure all air is out of rad before starting boiler.

 

[FrankM45]

Thanks Pete
Topped pressure up a little before I started, though couldn't get the gauge to move off the red, but decided I'd put enough in for time being.

I opened trv first then lock shield straight after. Bled out ok then started boiler, few gurgles during start up phase which lasts for about 15 mins on these, went round and checked other rads for air but all ok, after boiler finished its start up phase, all was fine. Pressure gauge rose just into the green so going to give it til the weekend to make sure it's stable then increase pressure up to 1.5 bar or near enough.
Many thanks for your help.

F

 

[FrankM45]

Hi Pete,
completely different subject - I will be refitting bathroom soon and will include a shower fed from the bath mixer tap (not sure what style or type yet) do you know if my system will provide enough hot water pressure?
Bosch Worcester green star 30cdi combi, located in garage; 3 bed house, 1 main bathroom 1st floor & 1 under stair sink & toilet.
Does the boiler pressure have any relation to hot water flow?

(Realise this query shouldn't sit in this post thread)

Thanks again

 

[45yearsagasman]

System pressure has no effect on hot water delivery, that is controlled by your incoming cold supply. They are suitable for a shower, but it's impossible to give you any actual performance figures.
I'm no expert on showers, but you boiler is designed for single point use and anyone turning on another tap during shower use will certainly affect the showers performance. Not sure of your boilers data, but it will only deliver approximately
11/12 litres per minute raised by 35 deg C. During Winter when the incoming water is, say 5 Dec C.........You do the maths.