where is your bleed pipe taken from to feed the expansion bottle..?
Re # 52
of the top of the return rail .
solves one problem but leaves no home for the water temp gauge connection . This would need to find a home in a submarine pipe .
may not be needed ? The bypass could possibly be
Teed into the existing pipe that runs from the expansion bottle to the thermostat housing .
I might be interested in trying this but just want to understand a couple of things
By introducing this larger bypass pipe from the back of the block to the thermostat housing it follows basically the same path as the bleed pipe via the expansion bottle . Larger flow but the same path .
what benefits does the larger flow give ?
All the plastic HE14 thermostat housings I've seen place the bypass connection next to the cold feed from the radiator . The 620 has a metal connection to the block .This seems distant from the thermostat . Will the thermostat still operate correctly using this connection or will one just end up with a large volume of water circulating round and round the block ?
Not looking to be awkward here just trying to understand the implications of changing the rear connection manifold .
Increased water flow Mark, the T'd off via the expansion bottle pipe flows tro a 3-4mm hole, the bypass is a 16mm hose, the response time of the hot water from the head to stat is quite different, it also allows for a much better warm up circuit too.
No, the 16mm plastic connection on the stat hosusing is the return line from the expansion bottle and heater - usually the bottle is T'd into the heater return, the bypass is the gold colour metal pipe pressed into the block itself which directs hot water straight onto the wax capsule, this circuit is open to flow during warm up and as the stat opens in response to the hot water from the bypass the stat then closes this bypass off in favour of the 32mm return from the rad - but should the stat receive too much cold water from the rad it will start to move in the opposite direction thus reopening the hot supply form the bypass this blending effect much like a domestic shower maintain your base temperature.
OK, what about the stat end, what needs to happen there?
So just to be clear , bypass from new back plate to connection shown in this photo ( black pipe )