mystery valve?

[simon13]

the above picture shows the cylinder , 3 port valve and pump in my central heating/hot water system .I have an indirect coil type cylinder, with connections as shown in the diagram, with the heated water from the boiler flowing through these connections.i have no idea what what this mystery valve does as it appears to do nothing.its been suggested to me that this is a " balancer valve"( i just smiled and nodded politely)can anyone out there tell me what it is and what position it should be in (open or closed)
cheers in advance.

 

[noonespecial]

What have you got there Both flow and return connections to the cylinder taken from the boiler flow If so it is wrong.

Looks as though you have a gate valve on the flow and the return to the cylinder. You only need one valve and that should be a regulating valve and not a gate valve. Gate valves do not have regulating characteristics and are only intended for hydraulic isolation purposes.

Also why have you got PTFE tape on compression joints

 

[chrishutt]

The gate valve is a by-pass valve. It is very commonly placed in that way connecting the flow after the pump and before the motorised valve with the return pipe.

It is only necessary to have it open if you have TRVs on all your radiators, since they could theoretically all close at the same time and prevent any flow taking place, causing the boiler to overheat. The valve only needs to be open enough to allow a minimum flow through the boiler in these circumstances.

 

[corgiman]

or if you have a boiler with a pump overruning as well chris as the valve can shut off and stay in central heating only Position

 

[chrishutt]

Corgiman, the diverter valve is always open to at least one circuit (CH or DHW). If it shuts off in CH open position the pump overrun will function properly unless all the rads are shut, which is only likely to happen if they are all fitted with TRVs. It would be more logical to fit the by-pass between the CH circuit flow and return.

 

[corgiman]

I am only going by most MI instructions and they state a Automactic by pass must be fitted

 

[chrishutt]

Now they do, but at the time this installation was probably made gate valves were all that was required.

 

[corgiman]

Like the man in orthopedic shoes "I stand Corrected"

 

[noonespecial]

Egg on my face and damage done Cant see return out of cylinder and so my over worked brain decided the bypass was connected to the return connection. I do feel a plonker

 

[corgiman]

You and me both

what do you say to us packing in this plumbing milarky and starting up as talent scouts for brothels mate?

 

[Agile]

We did a boiler repair in one a couple of weeks ago and I was not very impressed by the talent there.

The weekend maid was very friendly and made us coffee and gave my trainee a £4 tip!

The weekday maid was not so friendly, made no coffee and gave no tip.

Tony

 

[lor]

so you maid sure to return then ?

 

[Crystal]

Boiler delta t adjustment.

 

[simon13]

thanks guys it must be a by-pass valve because there are no thermostatic radiator valves in the house(built buy barrets in the early 90`s).
I`ll leave it slightly open then without worrying about blowing things up.thanks again

 

[ACOperson]

To 'noonespecial' : In a relative of mine's house the cylinder flow is taken from the boiler flow, and then the return from the cylinder goes back into the flow pipe.

Its worked fine for nearly 30 years!

I know its not right, but it can work...

BTW, I'd leave that gate valve as it is matey, if it aint broke, don't fix it!