Honeywell Straight Auto Bypass Valve 22mm
I can't recommend these valves. I have now had to replace mine for the second time as the two I've had both failed within two years of fitting. They both got stuck partially open causing permanent bypass. Even when brand new they were imprecise in operation and difficult to adjust correctly. I used the Honeywells as my pipe layout could only accommodate a straight valve. I've now reworked the pipework so I can use the more common angled type and the valve I've now fitted works better than the Honeywells ever did.
18 Apr 2013
Another reliable and quiet product from Honeywell if a little expensive
8 Oct 2012
Every system should have one
After having problems with badly adjusted bypass ccts - a revelation. Just fit this in place of the old Gate valve, adjust for min boiler requirement and its done - maximises efficiency and prevents problematic overheating - especially when using multiple TRV's. Â£30 is a bit steep - but will probably save that in gas bills very quickly. Long term reliability remains to be seen - but no problem so far.
5 Feb 2009