Mr Gasman's May service of our 1984 Potterton Netaheat showed that it burns very well, with zero CO output. I was warned that no replacement will match its long life and have no intention of being proactive about replacement, but one needs to be prepared.A few months ago I was informed here of the benefits of unvented heating primary circuit. If I was installing from scratch, I would not be having any qualms. However, there is precisely zero access underneath the floor-boards in most of the house, unless I cut through the hard-wood flooring.So, what is the chance of introducing leaks underneath the floor when swapping from vented to unvented primary in a 25+ year old installation? And what other complications should I expect from the lack of access?Thanks in advance for any opinions,Kostasp.s.: The other thing Mr Gasman suggested was installing a (Vaillant) combi and running it as a heating-only boiler with an unvented secondary, since I am not keen on the HW aspects of the combi. I think the motivation is he can get it cheap, because he buys so many of them. Thoughts?

What are they then?If it ain't broke don't fix it. The biggest leak will develop in themost in accessable place 5 mins after you have gone away for theweekend and bring down the ceiling and ruin the brand new carpet ofthe room you have just finished decorating...

Pressurising heating primary; where can it go wrong?

Jul 10, 2011 21 Replies

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John Rumm 15 years ago

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>>> I forgot about that yesterday. I have a Honeywell CM-zone system. When

That's the traditional solution. Usually the room with the stat, has no TRVs on the rads.

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Kostas Kavoussanakis 15 years ago

There is no room with a stat in my case. All the rads (can) have a stat. The CM Zone literature suggests all rads should have a TRV, either their fancy one or a generic one. I am not sure how this would work when pump over-run kicks in, but I am sure I don't want to experiment. :-)

Kostas

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