Vented indirect cylinder venting issue

[Richard Simmonds]

A customer of mine lives in an old cottage that has been extended. They have three loft areas that are completely separated. The CWSC is in one higher loft space, the hot water cylinder and shower pump live in another lower loft. They are on different sides of the building. There is single 22mm pipe that serves as both the vent and a hot water feed to running to the side of the house containing the CWSC in which there are two three bath/shower rooms. There is a separate hot water feed to the utility and kitchen that are in the "wing" beneath the hot water cylinder.

At some point previously, someone decided to fit a whole house pump to the hot water feed coming from the cylinder. However in doing so they effectively separated the vent pipe from the cylinder as the pump now sits between the cylinder and the vent which as I stated also acts as the hot water feed to the other side of the building. Further more this has been teed off from the feed other bathrooms. Clearly this is a highly unstable and dangerous situation as there is no way for the cylinder to accommodate the expansion of heated water, apparently a previous copper cylender split so they replaced it with a steel one! My problem is that it is almost impossible to run a seperate vent pipe back to the CSCW or to separate another hot water feed from the existing pipework as most all of the pipework is buried deep into the fabric of the building and is inaccessible and there is no direct line of site between the to loft spaces.

I was called in to investigate why the shower pump kept failing initially and quickly realised the wider issue. I have resolved the risk in the short term by separating the pipework and establishing the vent pipe connection back to the cylinder, but now there is no pumped hot water back to the other side of the building and clearly the head of pressure is not very good. Ideally I am looking for a way to safely vent the cylinder then reconnect the hot water to the whole house once again, and cap of the old vent pipe but running a seperate vent pipe to the CSCW is not an option.

Is anyone aware of an alternative solution to safely vent a vented hot water cylinder when the CWSC is not accessible?

 

[SJB060685]

Picture of current setup? Surely there’s enough room to do a bit of repiping?

 

[Richard Simmonds]

Picture of current setup? Surely there’s enough room to do a bit of repiping?

If there was I would have done it. The existing plumbing is buerird into the fabric of the building in such a way as to render it inaccessible. The building is finished to a very high standard and the customer is reluctant for for me to start drilling and channeling through walls. This is why I'm exploring the concept reventing the cylinder in the first instance.

Picture of current setup? Surely there’s enough room to do a bit of repiping?

 

[Chuck]

the customer is reluctant for for me to start drilling and channeling through walls.

Point out to them that when a hot water tank fails the house is often uninhabitable for the best part of a year. Also, it's possible that their insurance will say that the damage isn't covered.

Can you side-step the problem by converting the DHW to a proper unvented system? Even if the service pipe to the house is undersized it may be cheaper and less disruptive to upgrade it than to install a duct, or whatever you're planning, between the two sides of the house.