Bypass on y plan

[Matt0029]

Does a y plan need a bypass between the pump and the 3 port valve. If there is no pump over run?

 

[ShaunCorbs]

No don’t need one

 

[Matt0029]

That's the current set up. I didn't think it needed one as there wasn't a pump over run. 3 way valve shuts, or goes to mid position? As the pump stops

 

[SJB060685]

The mid position valve holds the last port of call, unless you remove all power from the system, in which case it spring returns to HW port, if not already there. Unlike a NC 2 port, it will always have a port open.

 

[Matt0029]

So at no point can the mid position valve be totally off like a 2 port valve so no bypass is really needed even if the pump had over run. Is that correct

 

[ShaunCorbs]

Correct

 

[SJB060685]

So at no point can the mid position valve be totally off like a 2 port valve so no bypass is really needed even if the pump had over run. Is that correct

Bang on buddy. One problem though is if CH was last port of call, then even without power to the boiler and pump the motor is still energised holding it in CH port. Because of this the valve head can remain quite hot to touch and burnt out motors are more common than on a 2 port. Obviously if in HW port the motor is not energised, has just spring returned to default position.

 

[Matt0029]

Ok I have to change the 3 port valve In this picture. I will probably keep the gate valve there it's been there for 20 years I believe the system is.

 

[Matt0029]

Can I also ask when refilling after fitting do you keep the valve in manual open?

 

[SJB060685]

The manual switch is for filling I believe, to help speed up the process and channel air into the higher points. Technically the system will fill without it but might be slower and cause air problems?

 

[ShaunCorbs]

I just remove the head and put the valve in the middle of the two seats

 

[Matt0029]

Thanks I was just looking at the set up again with regards to the bypass/gate valve. It goes in to the hot water primarys so if slightly open as a bypass should be it would warm the hot water coil at all times. Seems a strange set up.

 

[SJB060685]

In order for flow to occur there has to be a pressure difference and water will always take the path of least resistance.

 

[Matt0029]

Thanks yes, so in effect that gate valve/bypass will mean the hot water is always getting heated (slightly) when the central heating is on.

 

[ShaunCorbs]

Short circuiting more like and going straight back to the boiler

 

[SJB060685]

If its open for CH it will probably short circuit and go straight back to return. This will in turn cause the boiler to modulate down. The bypass needs to be installed between the common flow and common return.

 

[Matt0029]

Thanks so a strange place to fit a bypass. Plus isn't really needed as discussed earlier.

 

[ShaunCorbs]

Best to leave alone and just change the valve then you can’t be blamed for something not working or a rad not heating up

 

[Matt0029]

Does anyone known to get the actuator of this valve does the motor need removing?

 

[Matt0029]

Best to leave alone and just change the valve then you can’t be blamed for something not working or a rad not heating up

Thanks yes I did think of swapping as looked abit old. But don't want to change something if it's worked like that for 20 years though appears a strange set up.

 

[ShaunCorbs]

Eph valve I think

 

[Matt0029]

And just to confirm no bypass needed even if a pump over run was wired in on a system with a 3 port valve. As a 3 port valve is always open to one port? It doesn't shut off like a 2 port valve. Only really worked on S plans before.

 

[Matt0029]

Eph valve I think

Correct

 

[ShaunCorbs]

One port is always open on a 3 port you can shut them

 

[SJB060685]

I'd just shut that gate valve completely mate, or remove it. As it is its causing a short circuit, which in any demand is causing an underflow in each circuit and not good.