Help please! Issues with Central heating & Hot water

[garyevans]

I will start by saying I am not a plumber but I have learnt loads thanks to people on here. I am currently having an issue with heating & Hot Water. It is working but I have to do certain things to make it work each day. The question is about the 2 gate valves in the picture. Valve number 1 and 2 . I think from what I have looked at on google etc that 3 is the pipe taking hot water from boiler into the immersion heater which is on the left (we have an open vent system). The pipe under Valves 1 & 2, I think, is the cold water out of the heater back into the system? Should both valves (1 and 2) be open or just valve 2? When both are open quite a bit, it sounds like air is getting into the system and at that point the boiler stops. When both are closed, the pipes around the house make a loud clanging noise. As a result, to get Heating, I currently have to close both valves and the heating is fine. To get Hot Water only, I have to open both but only a little and sometimes this fails. My thinking is that of Valve 1 is open it is letting cold water into the hot water coming from the pump and that causes the issue? Currently, I cannot get both Heating and Hot water to work at the same time. Nightmare. The rads are hot around the house (all 14) when heating is on and when the water works it's fine - but it is rather hit and miss. I am convinced the issue is to do with the valves, especially valve 1. For info, the pump is currently on PP1 not CC3 as in the picture. Thanks!

 

[gmartine]

Open gate 1 fully and close 1/4 turn.
Close gate 2 fully and open 1/4 turn.

See what happens.

 

[garyevans]

Open gate 1 fully and close 1/4 turn.
Close gate 2 fully and open 1/4 turn.

See what happens.

That worked while the HW went on but a short while after turning the CH on too the pump started to make a noise that sounds like air rushing through and the boiler stopped. I have now tried the other way round. So gate 1 closed and open quarter turn and gate 2 open and closed quarter turn to see what happens.

 

[John.g]

Have you got a open vented or sealed system?.
Which way is the pump pumping, there is a arrow on the side of the pump body.
If the pump is pumping downwards into the 3 way valve then valve1 can't or shouldn't be the cylinder return.
What supplies the cylinder coil flow (top).
Mid position valve should be plumbed like below.

Surprised that PP1 can supply 14 rads as its max head is only 2M and only around 1M when/if supplying 14 rads, are you sure its not on CP1 which is a constant 3M?.

 

[garyevans]

Have you got a open vented or sealed system?.
Which way is the pump pumping, there is a arrow on the side of the pump body.
If the pump is pumping downwards into the 3 way valve then valve1 can't or shouldn't be the cylinder return.
What supplies the cylinder coil flow (top).
Mid position valve should be plumbed like below.

Surprised that PP1 can supply 14 rads as its max head is only 2M and only around 1M when/if supplying 14 rads, are you sure its not on CP1 which is a constant 3M?.

View attachment 80792

Hi John. You helped me a lot in a previous thread. (Any ideas? Unreliable heating. - https://www.plumbersforums.net/threads/any-ideas-unreliable-heating.128283/post-1159027) but the problem has persisted.
Open vent system. Pump is pumping downwards. Definitely on PP1 but has been ok on CP1 before. But it kept cutting out. At that point I had not even considered the valves below the pump but by many processes of elimination that's now the focus of my attention. 3 port valve is as per the picture. Since I changed the valves as above (2 hours ago) it has been fine. We shall see if it lasts. I think valve 2 is the boiler return.

 

[John.g]

I rememner now but can't understand why we didn't see the way that's plumbed in which "can't" work IMO except I'm looking at it all wrong.
The pipe into the pump top should come from the boiler flow (Hot), the pump should then pump it into the (AB) port of the midposition valve (which its doing) but you can't have a return teeing into this pipe as well?.
Can you see where A and B are on the midposition valve and if the pipe into the lefthand side of valve2 is coming from the cylinder coil return (bottom). Also what is supplying the cylinder coil top?.

 

[garyevans]

I rememner now but can't understand why we didn't see the way that's plumbed in which "can't" work IMO except I'm looking at it all wrong.
The pipe into the pump top should come from the boiler flow (Hot), the pump should then pump it into the (AB) port of the midposition valve (which its doing) but you can't have a return teeing into this pipe as well?.
Can you see where A and B are on the midposition valve and if the pipe into the lefthand side of valve2 is coming from the cylinder coil return (bottom). Also what is supplying the cylinder coil top?.

Photos show the set up. I think the pipe into valve 2 is coming from the cylinder coil return.

 

[John.g]

Can you identify these pipes, looks like the boiler coil flow (top) is teed in abve this with maybe the vent and cold feed, can you post a photo higher up?.
If the boiler coil flow if teed in like this then opening valve2 (and 1) means the HW will be pumped in through the boiler coil return and return back into the pump suction via the coil top. in effect a pump only by pass.
Valve1 also supplies a pipe going down through the floor, where is this from/to?

 

[John.g]

Think I can see it all a bit clearer now, the pump is pumping into the midposition valve, the MP valve top (B) pipe is connected to the cylinder coil flow top pipe correctly and the MP valve bottom (A) pipe supplies the CH.
The (bypass) pipe is incorrectly piped and should IMO be , as shown, if in fact required at all. In the meantime suggest keeping valve1 fully closed and valv2 full open or at the mimimum not less than 1 turn open in case you want to heat the cylinder on its own.

 

[John.g]

Also ensure that with valve1 fully closed that the pipe just above it is cold/cool to ensure valve not faulty/passing.
Just to be sure also check that the 3 way valve is a mid position valve and not just a diverter valve.

 

[garyevans]

Thanks John. I think you have got all that spot on. The piping has been like this since 1996 when the house was built. The issue started after BG fitted the new pump. The valves were not set right after that. Not being a plumber it has taken a lot of guess work and your posts on here for me to understand things. CH and HW still working with Valve 1 closed and Valve 2 open. The 3 way valve is a mid position valve as far as I know. I don't know what a diverter valve is.
Wirh regards to the pipe above valve 1. Do you mean the pipe actually going into the valve? That is hot when the heating is on.

 

[John.g]

I mean the vertical pipe in which valve1 is installed in, with that shut if you feel it anywhere between the valve and where I say *blank off here" then should be cold if valve holding.
A diverted valve is one where you can have either CH or HW on but not together. It will be written on the valve.

 

[garyevans]

I mean the vertical pipe in which valve1 is installed in, with that shut if you feel it anywhere between the valve and where I say *blank off here" then should be cold if valve holding.
A diverted valve is one where you can have either CH or HW on but not together. It will be written on the valve.

That pipe is hot when the system is on. I can't see how that would stay cold with the HW or CH on as the pump above is pushing the hot water down. The 3 port valve has W on the top, M in middle and H on bottom.

 

[John.g]

Feel the pipe where indicated (remove insulation) while the boiler has been firing for a hour or so, it should be coolish, then while still holding it, briefly open valve1 a few turns , does the pipe get hotter?. (there should be no flow through this secton of piping but it will be a bit warm from conduction.)

 

[garyevans]

Feel the pipe where indicated (remove insulation) while the boiler has been firing for a hour or so, it should be coolish, then while still holding it, briefly open valve1 a few turns , does the pipe get hotter?. (there should be no flow through this secton of piping but it will be a bit warm from conduction.)

I tried it when the heating reached thermostat temp and it was cooler than when the heating is on. I think conduction explains the hot pipe when heating is on. Opened valve 1 and you can hear the water flowing. Closed again. So far so good for CH and HW. Will keep monitoring. Thanks for your help.