COMBI SYSTEM ALWAYS REQUIRES BLEEDING!

[bolthebuilder]

I've been in my extended home now since September and I'm finding air in my towel rail every week. I have a Worcester Bosch Greenstar 35 CDi with TRV's on every rad except bathroom, which is a very tall towel rail. Unfortunately, the system was installed by the bert and ernie of local plumbing and we've repaired numerous leaks upon occupation. I've recently lagged all the pipes under the ground floor, so I'm sure there is no glaringly obvious leaks present. However, we did run out of money when completing the extension, so we didn't finish the en-suite. Therefore, we have to isolated ends where a second (smaller) towel rail should be. I recharge the system to 1.2 bar (recommended by W.B.) and always bleed a warmed system with heating off!
The system is in copper, therefore is my only solution checking every joint? Also, if I've got to get them back or have a plumber look at it, what's an acceptable figure for the pressurised test of the pipework?
Any help anyone can afford me would be greatly appreciated.

 

[Agile]

On a sealed system water normally leaks OUT and any gas in the system is as a result of corrosion.

It sounds as if your system was not properly cleaned or inhibited. What colour was the water you bled out?

How often are you repressurising and whats the start and finish pressures.

Unless there is a problem I dont advise you to keep bleeding anything.


Tony

 

[bolthebuilder]

Tony,

Thanks for the quick reply.

I have to top up system every other week after bleeding rad in bathroom.
Pressure is none existent before top up and I set to 1.2 bar after. Water is quite clear when bled.

Why would you suggest I don't bleed regularly? Is it because doing so would let more air in, therefore increasing risk of corrosion? As if I didn't bleed my hot water goes, which I can't allow!!

Ste

 

[Agile]

You are likely to be causing yourself problems by this bleeding you are doing! Its not necessary.

What you should be doing is setting to about 1.5 Bar cold and topping it up as soon as it goes below 1.0 Bar.

Tony

 

[bolthebuilder]

How cold is cold for top up? Not been on for hours or after say 1/2 hr?

Does that mean that the probable cause of the cold topped towel rail would be pressure (or lack of it!)?

Ste

 

[namsag]

What do you mean he is causing it by himself..
If the rad is emptying and system is losing pressure then he has clearly got a leak on it somewhere.
OP it doesnt take much of a leak to drop pressure over a couple of weeks . Check everything you can get to when hot and cold . might even just feel damp as opposed to dripping.
Also make sure pressure release pipe outside dosnt even have slight drip on it

 

[Agile]

I only said top it up when cold so that the pressure is consistant. Slightly warm rads are not a problem.

Presurise to 1.5 Bar and repressurise as soon as it falls below 1.0 Bar.

Tony

 

[lifesagasman]

OP you have a leak somewhere. thats where air gets drawn into a sealed system. go around every joint with dry tissue paper until you find it. having said that, the leak could be within the boiler