Closed system top up fed by domestic storage tank.

[squirrels tail]

I know of multiple estates built during the celtic tiger where the closed system heating is topped up by teeing into the cold feed to the copper cylinder using a check valve and expansion vessel left permanently connected. Recently went to one of these houses just to fit a new tap, but discovered while i was there that the vessel diaphragm and check valve had failed, allowing the heating system water to expand back up into the storage tank. I would be interested to know if anybody else has come across this issue.

 

[ShaunCorbs]

Nrv failed / stuck open

 

[squirrels tail]

Nrv failed / stuck open

Yes as stated the nrv had failed along with the expansion vessel, which they do. The point being that the system should not be supplied from the cold water storage tank, it should have it's own small tank. The problem being that when they do fail there are no warning signs and the water from rhe heating is going back up into the domestic cold water tank.

 

[ShaunCorbs]

Yes as stated the nrv had failed along with the expansion vessel, which they do. The point being that the system should not be supplied from the cold water storage tank, it should have it's own small tank. The problem being that when they do fail there are no warning signs and the water from rhe heating is going back up into the domestic cold water tank.

Depends on the cylinder eg primatic

Convert it to sealed

 

[squirrels tail]

Don't think primatic are meant for pumped system. But the issue being a plumbing connection between the radiators and the domestic hot water using 2 fittings that often fail. (Nrv & expansion vessel)

 

[Last Plumber]

Don't think primatic are meant for pumped system. But the issue being a plumbing connection between the radiators and the domestic hot water using 2 fittings that often fail. (Nrv & expansion vessel)

If this is an indirect cylinder then I personally have never seen a set up like you describe but it is something I would alter if I saw it and for the reason you give. It is a silly idea and can only lead to eventual mixing of the two waters. No one wants to bath/shower in heating water.

Primatic were not designed for fully pumped as you say but they were designed to allow for filling and expansion of the heating side.

I have to ask, what or who is Celtic Tiger?

 

[squirrels tail]

It was the boom time in Ireland from the mid 90's to about 2008. Cetic being irish and tiger a copy of boom economy in parts of asia, symbol of strength.

 

[squirrels tail]

Yes it is a silly idea, and will only separate the water for a limited time, until the vessel fails or just loses it's charge and the NRV can also fail. Try explaining to a householder that he needs to have his plumbing rectified which as far as he is concerned works perfectly well.

 

[Chuck]

Try explaining to a householder that he needs to have his plumbing rectified which as far as he is concerned works perfectly well.

I suggest that you politely explain that in your opinion that bringing the system up to standard would be an essential part of completing the job in the proper and workmanlike manner that you have built your reputation on. If he does not want a quote on this basis he will need to find another plumber who is willing to consider other approaches.

On the other hand, based of your description of the local housing stock, if you could devise a cost-effective method of bringing this type of system up to scratch you probably won't be short of customers.

 

[squirrels tail]

Sounds like a good idea, but i don't think it would work until there was some kind of government directive based on the public health issue. Government have been fully aware of this issue since 2015. Also it would cost money, who will pay.

 

[John.g]

That system might be known as a semi sealed system but obviously should not under any circumstances be kept topped up from the CWS cistern, it seems a bit strange that if these sealed systems were installed from new during those halcyon years as probably as easy to install the top up properly from the mains?.
There was no nat gas service to my > 50 year old housing estate so all oil fired central heating, incidentally, supplied from a central oil storage tank and metered to each house. Over the years a high percentage changed over to nat gas and some/most still retain the F&E cistern (semi sealed with EV & NRV), seemes a lazy way though to do it this way.

 

[squirrels tail]

Yes it would have been better to take the feed straight from the mains as systems are still being installed using a nrv and a constant pressure regulating valve at 1 bar with mains permanantly connected. With both of the above systems householders and plumbers don't have to worry about water loss from small leaks, rad valves etc. But as about the system topped up from the storage tank, once the nrv fails, heated water will have no restriction rising up to the tank bringing central heating additives and other pollutants.