Old A/B valve advice

Joined
8 May 2006
Messages
18
Reaction score
1
Location
Hampshire
Country
United Kingdom
I've got an ageing old Honeywell system plumbed into my house, and want to modernise it :) I've bought a Hive to replace it, and after carefully checking everything decided to replace. However the existing Honeywell brain (magic box) does all the work, e.g. the hot water cylinder has two wires that run to the brain, so isn't a standard 240v one (easy to replace). However the A/B valve is also wired into the brain and only has 2 wires, 240v neutral and positive, and the valve is all one piece (e.g. if I try to take the top off it leaks water)... So will I have to replace this with a more modern a/b/ valve (think 5/6 wire ones?) or is this usable? I can't figure out how it knows what position it is in... The motor works, not sure if the a/b does as my heating still comes on in summer... but the brain also has a couple of bad burn marks on it, so think bits of it maybe fried.
It's late I'm tired, that's probably useless info, but I can grab the info if more needed. Help welcome :) TIA

/\/\at
 
Sponsored Links
It's a Honeywell AQ6000 running system B I believe.
20190804_225249.jpg 20190615_110741.jpg
 
The system installed is designed with super efficiency in mind, the Hive much less so. The system will require substantial electrical and mechanical alterations to install. I'd recommend calling a heating engineer. (Or leaving it as it is!) The 'burn marks' are likely just dust drawn in from the components that run warm. The AQ6000 system was rather expensive to buy.
 
Sponsored Links
It's not been right for years, the heating always comes on with the hot water, so either the brain or valve is dead. Hence why trying to understand how the mid-position valve works with just 2 wires for power. As far as I can tell Hive can run all this no issues, it's just the mid-position valve as it needs to know it's position.

PS The burn marks smells of fried electrical components, and AQ6000 is 20+ years old now.
 
Oh dear! In that case you will need to convert the system to use standard heating control components, probably to a 'Y' plan with a 3 port mid-position valve and a cylinder stat.
 
Cylinder is easy enough, just the mid valve, which I guess will require a drain as doesn't seem easy to replace the a/b otherwise.
 
Drain system, new 3 port or split to x2 2 ports and a bypass. New cylinder stat. Rewire.

The existing system is a 2 wire valve and from memory it gets pulsed to open for the heating and the flow pipe sensor works out how much heat to put in. It’s like a VT circuit on a commercial heating system without the return mixing.

Clever concept, expensive to install and unfortunately, now obsolete due to lack of market take up.
 
Thanks, re-enforces my thinking.. I might have access to a pipe freezer, tad easier than a complete drain!
 

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.


Are you a trade or supplier? You can create your listing free at DIYnot Local

 
Sponsored Links
Back
Top