No vent pipe to F&E tank but is a vented system - need help to understand this

[Simon James]

While cleaning the airing cupboard I noticed the F&E vent pipe was not connected. The F&E tank water supply pipe connects direct to an air separator by the boiler. I assume air gets out of the system through this pipe via the bottom of the F&E tank. I have a vent pipe into the cold cistern from the hot tank and some sort of air release valve on the indirect pipe from the boiler into the hot tank. This air release valve has a nut on the top which seems to require manually opening to release the air?...

Should I put a vent pipe into the F&E tank by jointing to the F&E supply pipe?

The schematic diagram enclosed helps explain this odd arrangement.

Suggestions welcome - thanks, Simon.

 

[Ric2013]

Does your boiler's installation manual specify a traditional vent pipe is required? Some boiler manufacturers' literature allows a combined feed and vent pipe (usually in 22mm) to be used as the boiler itself incorporates overheat safety devices to prevent boiling. If this is your case, I don't really see the problem with your existing setup.

 

[Simon James]

Thanks for that Ric.
I'm not sure is the answer because British Gas fitted the boiler 9 years ago, 3 years before we came here. I have been told by the maintenance fitter that the boiler is a Gloworm but I'm not sure how to find the model number...
It's been ok during our tenure but it gurgles a lot especially after the system has been drained (to put in new rads etc). I'll see if I can do some digging...
But good point on your behalf - thanks.

 

[Ric2013]

Might be worth posting up a photo on here in case one of the gas guys can identify it?

 

[chris watkins]

You can still have a feed cistern which is in the loft that supplies & automatically tops up the water in a sealed heating system, it will have a non-return valve on the cold feed & no open vent just A.A.Vs to remove the air as you describe.
I can't see your PDF so working blind here but when you drained down the heating to change the rad where did you turn off the water & how did you fillet back up?

 

[Simon James]

Might be worth posting up a photo on here in case one of the gas guys can identify it?

Ric,
Please find enclosed two photos of the boiler - badged as a British Gas 330 condensing boiler. It is 18kW output.
I think I have found the right manual on installation and servicing. It states:-
1. A safety valve need not be fitted to an open vented system.
2. It requires an open vented water system - the vent must rise continuously and be unrestricted
3. For a combined feed and vent, a 22mm pipe must be fitted in accordance with BS5449.

Does point 3 mean my system is ok - it is a 22mm pipe...
Thanks, Simon.

 

[Simon James]

You can still have a feed cistern which is in the loft that supplies & automatically tops up the water in a sealed heating system, it will have a non-return valve on the cold feed & no open vent just A.A.Vs to remove the air as you describe.
I can't see your PDF so working blind here but when you drained down the heating to change the rad where did you turn off the water & how did you fillet back up?

Hi Chris,
I know it's not a sealed system as I have checked the line of the F&E pipe all the way to the boiler and it only has compression joints. When the system was drained down the F&E tank mains was isolated and the lowest drain tap was opened. Filling was the opposite.

I enclose a photo of, what I think is, the AAV just above the indirect tank feed. Is this an AAV?

Thanks, Simon.

 

[Ric2013]

3. For a combined feed and vent, a 22mm pipe must be fitted in accordance with BS5449.

Does point 3 mean my system is ok - it is a 22mm pipe...
Thanks, Simon.

It sounds like a combined pipe is acceptable then, if installed correctly.

 

[Ric2013]

That's a manual vent, not an AAV.

 

[Simon James]

That's a manual vent, not an AAV.

Ric,

Does that mean it should be opened occasionally to remove air built up in the hot water pipe system? Any problems with doing this myself?

Thanks, Simon.

 

[chris watkins]

As above, it is a 22mm combined feed & vent pipe, goes in & out of vogue but is perfectly OK just a bit more difficult to fill & vent the system when you drain them.

 

[Ric2013]

Ric,

Does that mean it should be opened occasionally to remove air built up in the hot water pipe system? Any problems with doing this myself?

Thanks, Simon.

Correct. I see no problems with you doing this yourself. No different from bleeding radiators really.

 

[quality]

Gloworm Ultracom first model

 

[CHRISX]

Hello All,

If I ever installed a `Combined Feed and Expansion` pipe to a Boiler I would extend the Expansion pipe from a tee where the cold feed joined the F&E Tank to up and over the Tank just like any other Heating Expansion pipe.

I would not put an Air vent above the tee as is shown in the photo of the Feed & Expansion pipe that the OP has posted on this thread.

To Me whoever installed that did NOT pipe the `Combined Feed & Expansion` correctly - although any Expanded water would still enter the F&E Tank in my opinion they did a `Sub standard job`.

Having the Expansion pipe installed `as normal` is obviously better for venting Air when filling up the system than having to keep checking a manual Air vent - and in my opinion is just a `Better job`.

Regards,

Chris

 

[chris watkins]

Chris the photo shows the flow connection to an old indirect cylinder, I believe.
So we would have to assure the system is a fully pumped S or Y plan if correct these valves would be able to isolate the open vent from the boiler if it were in place of that air vent, something we can't do!
An air vent is required on the cylinder as it is a high point.

 

[CHRISX]

Chris the photo shows the flow connection to an old indirect cylinder, I believe.
So we would have to assure the system is a fully pumped S or Y plan if correct these valves would be able to isolate the open vent from the boiler if it were in place of that air vent, something we can't do!
An air vent is required on the cylinder as it is a high point.

Hello Chris,

Thanks for pointing out that I had mistaken the compression tee etc. in the photo for a connection to an F&E Tank.

I had read the OP`s message asking whether he should install a Vent to run above the F&E Tank and then glanced at the photo somehow mistaking the compression tee as connecting to an F&E Tank as being what had been noted as a `Combined Feed & Expansion`.

Looking again I cannot believe that I somehow `saw that` / the side of a Tank from the photo !

As I made such a error I am not surprised that You wrote about the Air vent being required on the Cylinder Flow & Return pipework.

I apologise to All for my mistake regarding posting a message the content of which which was based on my mistaking the content of one of the OP`s photos.

However hopefully forgiving my error regarding the photo I can assure You [Chris] / all Members that I am a Heating Engineer, Gas Engineer & Plumber with over 50 years of experience in Plumbing & Gas and over 46 years of experience in Domestic Heating and that `normally` any details contained in my messages would be correct.

Thanks again Chris.

Regards,

Chris

P.S: I did have time to have deleted my previous message [written based on an error re. my perception of the photo] but I left it so that Member Chris Watkins reply to me and this message would make sense to other readers - rather than be referring to a non existent message.

 

[chris watkins]

Hi Chris
There is no need for such a full explanation / apology etc. We all make mistakes & it is very easy to miss things in photos posted by others.
I look forward to you picking me up on mine!
As I tell any one who will listen it is not the mistake that is the issue it is how you correct it that really matters. Thanks for your posting without the input there is no forum.
Chris W

P.S. 50 years that makes you even older than me.

 

[Simon James]

Hi Chris
There is no need for such a full explanation / apology etc. We all make mistakes & it is very easy to miss things in photos posted by others.
I look forward to you picking me up on mine!
As I tell any one who will listen it is not the mistake that is the issue it is how you correct it that really matters. Thanks for your posting without the input there is no forum.
Chris W

P.S. 50 years that makes you even older than me.

Thanks to you both,

My system is a fully pumped S plan with two zones valves. Neither zone valve can isolate the F&E pipe so I think we are ok there. The system appears to be designed and built well apart from this F&E pipe (which is possibly why a looped pipe was put in and not connected - which started this whole thread at the beginning).

My feeling is I should follow ChrisX 's advice and put a loop in from the joint into the F&E tank. This is easy to do and may help a little when filling the system.

I would like to ask advice as to whether I should replace the manual air release valve on the hot tank with an automated one. Any suggestions?

My boiler will need replacing in few years and I think I will put in a separate feed and expansion pipe as best recommended...

Anyway thank you all for your advice - much appreciated!
Cheers, Simon.

 

[chris watkins]

Simon
Have it converted to a sealed system now rather than wasting money, it is best practice and yes stick an a.a.v on in place of manual but install a valve before it.