Horizontal unvented cylinder problem.

[Dotski]

Hi.
I'm a general builder and have a basic knowledge in plumbing. I have recently had a 'Manco' horizontal cylinder installed in a clients loft next to a new boiler. The boiler and cylinder seem to have been installed properly as all runs well except for hot water. Basically the cylinder wasn't being heating by the primaries. The highest point on the heating circuit is this cylinder and if any air gets into the system it ends up in the cylinder coil which wont vent without a fight! Ive run a hose from the vent/bleed nipple on the primary flow to the tundish, closed the zone valve and opened up the filling loop, it eventually cleared the air from the coil. My concern is that although the problem seems to have been cured, what if (for what ever reason) air was to find it's way back in, I can't ask the client to do what I had to do? I would have thought that the boiler would be able to push the air though and then vent automatically. Manco claimed not to have experienced this problem before and have suggested that if it happens again let them know and they would look into it, which is good news. Anyone heard of this problem before or have any ideas?

Thanks

 

[matt1e]

Never came across one of these before, but I would thought that an auto air vent at the highest point of the pipe work leading from the top of the coil would suffice

 

[Dotski]

Thanks matt1e.
I fitted an auto air vent after going through all that grief so fingers crossed, though I shouldn't really need to cross'em? There does seem to be a design issue here?

 

[matt1e]

I agree there's been a design issue,but not its not with the manco cylinder,
I think your installer should have just used some "common"

Matt

 

[Dotski]

ha ha I did give him a clip round the ear for the auto air vent.

I have read a few other topics regarding problems with horizontal cylinders not venting....hope I'm not going to get recuring problems.

Big thanks Matt

 

[Agile]

Well if the design was as shown there should not be much of a problem.

I would still fit a "T" with a vertical upstand just before the cylinder on the flow and an auto air vent.

But I am sure I have seen some horizontal unventeds without any connections along the top!

Most of those I see dont seem properly supported so I dont like to go closer than 2m and I dont look too closely.

Tony

 

[Onetap]

The highest point on the heating circuit is this cylinder and if any air gets into the system it ends up in the cylinder coil which wont vent without a fight!

How does air get back in?

Open vented system with an F&E cistern, or a sealed system?
Cylinder flow and return the right way around?
Primary system flushed and treated with corrosion inhibitors?

 

[tamz]

The cylinder will be fine. All down to bad system design and possibly the use of a hutch full of speedfit