Air getting into my CH/HW system.

[playford]

Hi,

I've been having problems with air getting in from somewhere. I have a sealed central heating system running off of a potterton boiler and I have a twin impellor pump running off of the hot water tank with some sort of dual flange(see my previous post). Is there any normal places for air to get into the system or do I have to just check everywhere?

http://www.diynot.com/forums/viewtopic.php?t=85306&highlight=

Thanks in Advance
Playford

 

[ChrisR]

This doesn't need a new thread...

 

[playford]

It's now no longer just about my shower though.

 

[Softus]

You say that air is getting in, but where is it coming out?

And since this a new thread, how much air? And how often? And when you do what?

And what pump do you have? And what shower valve? And everyfink?

 

[playford]

Ok, we'll start with the shower. its an Aqualisa pump, not actually sure of the model at the moment. I have a Powerforce mixer and have just replaced the hose and head with a screwfix one.

The CH system is a sealed system with 5 rads downstairs, 1 with a trv and 4 upstairs, again 1 with a trv.

I had a plumber in a while ago to fix some CH problems after a radiator fell off of a wall during decorating. While he was there a problem occured with the boiler when his apprentice was there blowing the pcb on the boiler. He was there for about 8 hours over a few days as well as the pcb and I never recieved a bill from him so I don't know if he did something.

During the time with the CH drained the pump started running dry so I replaced the pump with the same type from B&Q and also found a crushed microbore pipe running between the bedrooms which is the feed for the lounge rad and replaced this using compression fittings. When the boiler fires up at the moment, there is a bang or a thud from inside the boiler and occasionally the boiler trips itsself during cold weather( i believe this is when it overheats). you can also hear air around the pump and also sometimes you can hear air in the rads. I bleed the rads last night and found only 1 to have a lot of air in, it's the upstairs one with the TRV. Also the pressure guage in the airing cupboard rises over time.

The hot water problem is with the shower. In the morning I get no pressure from the hot water and you can hear lots of air in the pump. Last night i found that the hot water inlet to the pump was loose so I tightened that. I then ran the hot and cold tap in the kitchen to release the airlock if there is one and then ran the shower for 10 mins on full hot with no problems, but this morning the pressure was gone again.

I really started to get annoyed with this so I hope someone can help.

Thanks

Mark

 

[playford]

Nobody got any ideas?

Thanks

Mark

 

[gas4you]

Initial reaction is that pump is not spinning on boiler. Classic noises of no circulation.

As for the lack of water in shower, I would check that your cold feed cylinder in loft is large enough to cope with demand of shower pump, as if not it could be emptying and sucking in air each time causing the air locks.

I would expect you to have 1 x 50 gall tank or 2 x 25 gall tanks as a miniumum in loft

 

[playford]

Thanks Dave- going to look into that.