central heating advice sought please

[devonwoody]

I keep hearing air in our c/h system.

Sometimes however it is running peacefully and no air to bleed.

Pumped system and hot water tank (indirect tank), New Mexico boiler 12 years old the type with balanced flue, not one of these later type systems.

I have been bleeding the system perhaps two or three times a week this winter. (it has been running 12 hours a day lately)

Not running as hot this year as previous years.

Do I have a leak somewhere?

(no signs of leak at boiler or external pipes anywhere)

Do you have any ideas or advice please.

 

[RogerS]

Ask on askthetrades.co.uk

 

[devonwoody]

Ask on askthetrades.co.uk

I would be embarrassed to ask not having had past membership and going in heavy like that.

 

[stevenw1963]

I would suggest you have more than 1 leak.
You shouldn't need to bleed radiators that often.
Leaks could be anywhere & may not be visible i.e under floorboards if that is where your pipes are routed.
I would suggest getting a plumber in.

 

[RogerS]

Ask on askthetrades.co.uk

I would be embarrassed to ask not having had past membership and going in heavy like that.

Not at all...they are extremely helpful and knowledgeable

 

[devonwoody]

I would suggest you have more than 1 leak.
You shouldn't need to bleed radiators that often.
Leaks could be anywhere & may not be visible i.e under floorboards if that is where your pipes are routed.
I would suggest getting a plumber in.

Stevenw that what I am suspecting.

Going up the loft and shut off the supply tank to the system and see how much that drops over an hour etc.


Its too cold at the moment to do anything drastic, are there any sealers that work for a while ?

 

[dj.]

It would be very unusual to have a leak for the time period you suggest & not see signs of that leak, though it`s not impossible.
The easiest way to tell if an open vented system is leaking is to look or listen as to whether the ball valve in the header tank is running, best done when the system is turned off.

I would also suggest you take a look at the header tank when the system first fires up & also monitor it while the system is running, what you are looking for is water running out of the vent pipe, usually a U shaped pipe suspended over the tank.
If you are getting water discharge from this pipe then there are a few factors that could be responsible but you need to determine if this is happening first.


Regards.

dj.

 

[devonwoody]

Sound like a trip up the loft and watch the tank.

The header pipe, is that what I call the expansion pipe that runs up out of the boiler into the loft and then drops back open into that open header tank?

Cant be a bad leak because it might run ok for a couple of days?

 

[tsb]

Check your pump speed! If its on speed 3, try slowing it down to speed 2 or 1 and try it for a day or two. Depending on the design of the system, it is possible for the pump to suck air in

 

[RogerS]

Check your pump speed! If its on speed 3, try slowing it down to speed 2 or 1 and try it for a day or two. Depending on the design of the system, it is possible for the pump to suck air in

Only if it's on the wrong side of the boiler

 

[devonwoody]

pump is 29 years old, yes yes yes, and only one speed available so that wont suit.

 

[DIY Stew]

DW

When you bleed the system is the heating turned off? As far as I am aware you should not try to bleed the system when it is on as this can introduce more air.

Stew

 

[devonwoody]

DW

When you bleed the system is the heating turned off? As far as I am aware you should not try to bleed the system when it is on as this can introduce more air.

Stew

yes I suppose it is on when I have bled because I heard the air bubbling so went and did a bleed.

So next time I get the problem I will see if it bleeds properly doing it at the shutdown position.

 

[RogerS]

DW

When you bleed the system is the heating turned off? As far as I am aware you should not try to bleed the system when it is on as this can introduce more air.

Stew

I'm sorry but that just doesn't make sense to me. If the pump is running then the system is going to be under pressure.

 

[Russ59]

Have a look through this forum. I found a lot of info to a problem I had.

http://www.ukplumbersforums.co.uk/forum.php

 

[stevenw1963]

You should only pressurise a C/H system when it's cold.
You should bleed the system when it's on so it forces the water through the system.

 

[Russ59]

You should only pressurise a C/H system when it's cold.
You should bleed the system when it's on so it forces the water through the system.

This site says bleed while system is turned OFF, which is what I have always done with advice from my brother in law who is a plumber.

http://www.homeserve.com/help-advice/bo ... iator.aspx

 

[DIY Stew]

DW

When you bleed the system is the heating turned off? As far as I am aware you should not try to bleed the system when it is on as this can introduce more air.

Stew

I'm sorry but that just doesn't make sense to me. If the pump is running then the system is going to be under pressure.

If you bleed a central heating system with the pump on you will draw more air in, see the link below

http://www.homeserve.com/help-advice/bo ... iator.aspx

Stew

 

[RogerS]

DW

When you bleed the system is the heating turned off? As far as I am aware you should not try to bleed the system when it is on as this can introduce more air.

Stew

I'm sorry but that just doesn't make sense to me. If the pump is running then the system is going to be under pressure.

If you bleed a central heating system with the pump on you will draw more air in, see the link below

http://www.homeserve.com/help-advice/bo ... iator.aspx

Stew

They are partly right. It depends on where the pump is fitted. If the pump is in the flow (where it should be) then it doesn't matter one whit. The system is under positive pressure and so no air can get in. But I'm guessing that they are covering themselves for the odd plumber who sticks the pump in the return.

The only other possible reason is if it is a major bleed and that there is going to be a lot of cold water going into the boiler and the boiler is hot then that 's not a good idea. Nothing at all to do with getting air into the system, though.

 

[DIY Stew]

If you bleed a central heating system with the pump on you will draw more air in, see the link below

http://www.homeserve.com/help-advice/bo ... iator.aspx

They are partly right. It depends on where the pump is fitted. If the pump is in the flow (where it should be) then it doesn't matter one whit. The system is under positive pressure and so no air can get in. But I'm guessing that they are covering themselves for the odd plumber who sticks the pump in the return.

The only other possible reason is if it is a major bleed and that there is going to be a lot of cold water going into the boiler and the boiler is hot then that 's not a good idea. Nothing at all to do with getting air into the system, though.

Roger

I have checked 10 different web sites and phoned 2 plumber friends (both are also Gas Safe) and all have said you must turn off the heating before you try to bleed your radiators, if you don't you will draw air into the system! I too thought tha same as you, but when given the advice of professionals I accepted they were right.

Stew