First radiator in loop on open vent system...

[littlepigeon]

Hi all,

My bathroom radiator which i think is the first radiator in the loop always needs bleeding. When the heating is in use you could bleed it every day if you wanted. Within a week nearly the whole rad is cold

When i shut this radiator off i think from what i remember the air moves down the line.

Any ideas what to look for to find the problem? How would a plumber or central heating engineer attack this?

many many thanks all
Gav

 

[Mountskip]

You are probably drawing air into the system, which is replacing water. Air is much 'thinner' than water and can be drawn in through rad valve seals, although there need not be any water, as such, leaking out. Look for where the water is going, limey deposits around valve stems, plugs etc can indicate where air could be drawn in

Check the 'air' you are venting from the radiator, open the vent slightly and hold a lighted match in the flow, if the 'air' burns, it is hydrogen generated by electrolytic corrosion, or methane from biological activity; both resolved by adding a good inhibitor via the header tank.

Does your header tank overflow pipe drip. Could your boiler, or pipework, particularly underfloor, be leaking out of sight. Check that you are not pumping water over the system vent pipe, particularly when the circulation pump starts up.

It is essential that you resolve the situation, or you will have a severely corroded system, possibly involving complete replacement.

It seems that this might be a long standing problem, which, if it is, means that your system will have built up quite a lot of corrosion sludge, and will need properly flushing out.

You should be prepared to call in an expert heating engineer, whatever he costs will be an awful lot cheaper than replacing a corroded system.

 

[barkie1]

I would be looking at system lay out. Check correctplacement of pump, feed and the vent. Also checking the vent for correct hight to allow the expanison and contraction the system water. Just a few things to check first. Solutions could be alterations to layout, auto air vents? Or even changing the system to a sealed system?

 

[bengasman]

Radiators are not in a loop ( or at least should not be ), they are parallel to each other.

 

[littlepigeon]

Thanks all, i will look into this.

Cheers
LP

 

[littlepigeon]

Just out of interest if it was a corroded system would i not find i need to bleed all the radiators? Its only this one and is the first one the water comes to from the tank in the loft?

Cheers
Gav

 

[dcawkwell]

My guess would be the pump, vent and cold feed are incorrectly
piped and therefore the pump is dragging air into the central heating.

 

[littlepigeon]

My guess would be the pump, vent and cold feed are incorrectly
piped and therefore the pump is dragging air into the central heating.

Ok so looks like it's not corrosion as the air coming out of th eradicator blows my lighter out.

When I look at the set up of the pump and vent how should these be placed? What would I be looking for that would suggest they are piped wrong.

I need to ask as I know the guys that installed this are useless and they will try anything to baffle me with there schpiel as they tried when they had wired all the valves and clocks up wrong.

Many thanks
LP

 

[dcawkwell]

Correct arrangement should be

boiler , expansion pipe, cold feed, pump
Ideally with about 1ft between the expansion and cold feed.

When replacing boilers I only fit sealed systems never heat only boilers.
So never any problems with air getting in the system.

Seen one housing estate in Retford all installed wrong their boilers and central heating all rusting out at a similar time.

 

[littlepigeon]

Correct arrangement should be

boiler , expansion pipe, cold feed, pump
Ideally with about 1ft between the expansion and cold feed.

When replacing boilers I only fit sealed systems never heat only boilers.
So never any problems with air getting in the system.

Seen one housing estate in Retford all installed wrong their boilers and central heating all rusting out at a similar time.

Ok ... Well mine looks instantly wrong straight away then as from my boiler there is a pipe with the pump attached about a foot of pipe work away with an arrow pointing away from my boiler. Where this goes i dont know as i cant trace the pipe work to easy but i guess this is a problem straight away?

 

[dcawkwell]

Sounds wrong.

If your boiler has a high limit stat and is suitable I would go to
a sealed system. You can buy a kit that includes expansion vessel etc.
Therefore remove the central heating header tank from the loft.

My preference would be a new boiler all in one package.
Job done.

 

[littlepigeon]

Sounds wrong.

If your boiler has a high limit stat and is suitable I would go to
a sealed system. You can buy a kit that includes expansion vessel etc.
Therefore remove the central heating header tank from the loft.

My preference would be a new boiler all in one package.
Job done.

I'm gathering the pump would still be needed though and would still be in the wrong place?

Whats th benefits of the sealed ove open vent?

 

[dcawkwell]

Pump can remain where it is.

No air enters the system from a header tank. No header tank.
No wasted heat going up into the loft. Less pipework needed.
Reduced corrosion.

Pump can pump harder and therefore drive the water to more radiators and bigger distances.

 

[littlepigeon]

Pump can remain where it is.

No air enters the system from a header tank. No header tank.
No wasted heat going up into the loft. Less pipework needed.
Reduced corrosion.

Pump can pump harder and therefore drive the water to more radiators and bigger distances.

Now this sounds like a plan.... My water tank is still up there so that would need tackling at some point but the heating is a bit Cack to be honest.

So I can get a kit to do this? If I was to ask a plumber to do this is it a big job? Any info for me to read up in anywhere?

Many thanks for all info, this is a great help.

 

[dcawkwell]

Any plumber/gas engineer should be able to fit it.

Drain system down.

Cap piping to feed and header tank.

Then expansion vessel, pressure relief valve, pressure gauge and filling loop required.

Make sure the boiler you have is suitable for a sealed system.