Three port valve

[njmorrison]

Hello all, I've just replaced a hot water cylinder so had to drain down the central heating system. Prior to me doing this work the flat occupier was having trouble with the radiators coming on when only the hot water was set to come on. This was diagnosed as the need for a three port valve which was subsequently fitted.

Since I have replaced the cylinder the radiators are again coming on and the hot water isn't. I have very little experience with heating systems and three port valves but I suspect the valve needs to be re-set. Is this the case?

If so, is this done externally as I know there is a switch on the outer casing of the valve?

Pleas advise, thanks

 

[bathroomboy]

Have you checked for airlock in cylinder coil?

 

[unguided1]

are you sure that you have installed the correct cylinder, wired it all up correctly, piped it all up correctly, sounds to me like you need to find someone to check what youve done

 

[njmorrison]

It's an indirect system and I know all the connections are correct. The other thing is it's making a banging noise when the boiler fires up which obviously suggests air lock! I've bled all the ratiators but not sure how to purge air that may be trapped in the coil! The hot water draw off works fine the immersion heater works fine and the flow and return from the central heating are exactly as they were to the original cylinder, I just had to adjust the pipe work position slightly!

 

[Bernie2]

Basically, a three port valve, depending on whether its a diverter valve or its a diverter valve with a mid position ability works a bit like this.

The diverter valve, the water comes in the inlet port and out of one other port, when switched it comes in the same inlet port and out of the other port. In other words it comes in one port and out of another.

A mid position does the same thing but can also come in the inlet port and out of both other ports at the same time.

So if the valve is working and switching to DHW then something must be stopping the water from flowing through the cylinder the usual cause is trapped air.

Try cracking the backnut on the cylinder and holding a bowl under it, to let some air or water and air out if there is any.

Shut any by-passes, stepup pump speed and let the full force of the pumped water flow through the cylinder. Open by-passes gradually and balance system and pump speed.

 

[unguided1]

is there an aav on the primary flow into the cylinder

 

[njmorrison]

There is an aav, just next to the 3 port valve! Should I use this to purge the air? Other than that, I was wondering if I could attach a hose to the mains and force water through the F&E tank pushing the airlock through to the vent pipe? I don't really want to be undoing connections now as it's a very tight space and catching a drip in there is difficult enough let alone catching flowing water!!

 

[Puddle]

check you have fitted valve correct way round..heating/hot water port,if you turn heating on only at clock or turn room state up and cylinder state down do you get hot water only
if you have flow restricting valve on hot water return check open ok

 

[njmorrison]

The 3 port valve was already fitted, I haven't touched that. It was working correctly before I replaced the cylinder!

 

[unguided1]

I take it there is a cylinder stat on the cylinder and it is turned up to 50 degrees

 

[njmorrison]

Yes there is a cylinder stat!

 

[unguided1]

hi I have sent you a private message with my home number give us a call it will be easier
regards
Mike

 

[david williams]

is the aav between valve and cylinder,is hot water side of valve level with or below primary conection.does aav work?.

 

[bigcheese]

Does the pump make excessive noise? You could try stopping and starting pump by holding between 2 of the speeds and putting it back again. Do this a couple of times and it usually gets rid of air locks for me.