3 Port Valve problems

[slipperz]

Hi All this is my first post so go easy!!

My central heating system is a conventional open tank jobby with hot water cylinder with a 3 port mid position valve, room thermostat and cylinder stat with a Siemens RWB9 programmable controller.

For years when i selected HW the radiators got hot too. I got cheesed off with this, so i bought a new 3 port valve :- Honeywell V4073A Motorised Mid-Position.

I electrically isolated the system (i'm a qualified electrician) and drained down the hot water and radiators and fitted the valve and wired it .I also added some system cleaner into the header tank (i have a feeling this bit was wrong)
Radiators all filled and bled, HW de-isolated.
Now when i first fired up the system HW only the system was working correctly and the CH port was still cold but today it's hot again with the HW on heating the radiators!!! Have I maybe got some dirt trapped in the ball of the valve do you think from the cleaner or dirt from the header tank??
There is also a gate valve 22mm coming from the bottom of the cylinder I closed this in when I was taking out the valve, I have opened this again fully but i did not know the original position of this. I have read today somewhere else this may be a balancing valve to the heating coil?

Any help would be greatly appreciated

Slipperz

 

[bellairaphon]

The balancing valve sounds like bypass valve which needs to be closed as not required with a 3 port. Whilst the hot water is selected check what voltage you are getting on the white wire.

Nath

 

[slipperz]

The balancing valve sounds like bypass valve which needs to be closed as not required with a 3 port. Whilst the hot water is selected check what voltage you are getting on the white wire.

Nath

Thanks for the reply Nath.

The white wire - is at 6v to N / E with HW selected

The gate valve comes off the bottom of the cylinder and disappears down stairs (22mm)

Regards

Slipperz

 

[Hugh Jaleak]

Suspect the gate valve may be to restrict the flow through the coil when HW and CH are on at the same time. Prevents lions share of flow taking easiest path through the cylinder rather than around the rad circuit, which could lead CH to struggle until HW is satisfied and valve closes to HW, making flow go to CH.

Could be worth a look in the Central Heating FAQ's, D. Hailsham has a post on how a Mid Position Valve works, may be of some use. (As an electrician you might understand it as well! ) //www.diynot.com/forums/plumbing/boiler-central-heating-faqs.175736/page-2 (FAQ No. 17)

 

[slipperz]

Suspect the gate valve may be to restrict the flow through the coil when HW and CH are on at the same time. Prevents lions share of flow taking easiest path through the cylinder rather than around the rad circuit, which could lead CH to struggle until HW is satisfied and valve closes to HW, making flow go to CH.

Could be worth a look in the Central Heating FAQ's, D. Hailsham has a post on how a Mid Position Valve works, may be of some use. (As an electrician you might understand it as well! ) //www.diynot.com/forums/plumbing/boiler-central-heating-faqs.175736/page-2 (FAQ No. 17)

Many Thanks. I had printed those out to go through.
Think I will make a fresh start in the morning with a clear head and go through the procedure.

Are new valves ever faulty? I bet they are sometimes!

Slipperz

 

[Armo74]

If it is a manual bypass its better to consult the manufactures instructions for the boiler as you may require one if your radiators have TRV's.

 

[Hugh Jaleak]

My money would still be on a wiring fault rather than the valve. The valve will 'rest' open to HW/closed to CH as the spring returns it to that position if power is not present. (Override lever is in Auto, and not locked into Manual position still?) Even with some muck in there preventing the valve from seating correctly, I would still expect the CH side to struggle as there is greater resistance in the circuit compared with HW side, especially if the gate valve on the cylinder return remains fully open.

If the system has never worked properly, it seems odd that it 'worked' on initial testing, yet has now replicated the exact fault you were attempting to fix in the first place! (Also worth checking valve is fitted the right way round (and I'll get this right today!), port A to CH and B to HW.) Good animated diagram for Y plan wiring here if needed? : http://octaveblue.co.uk/central_heating.html

 

[slipperz]

My money would still be on a wiring fault rather than the valve. The valve will 'rest' open to HW/closed to CH as the spring returns it to that position if power is not present. (Override lever is in Auto, and not locked into Manual position still?) Even with some muck in there preventing the valve from seating correctly, I would still expect the CH side to struggle as there is greater resistance in the circuit compared with HW side, especially if the gate valve on the cylinder return remains fully open.

If the system has never worked properly, it seems odd that it 'worked' on initial testing, yet has now replicated the exact fault you were attempting to fix in the first place! (Also worth checking valve is fitted the right way round (and I'll get this right today!), port A to CH and B to HW.) Good animated diagram for Y plan wiring here if needed? : http://octaveblue.co.uk/central_heating.html[/QUOTE]

Many thanks again for the reply, and those diagrams will come on handy!

The wiring is a real snakes wedding and not as per most diagrams that I have seen online so far (only utilises 8 terminals instead of the 9) , although everything seems to tie in correctly, I will double check everything today including the valve is in the correct way.....B for bath!
Your probably right it has never worked correctly in the first place

I tried HW again last night and port B was red hot which is normal and port A was warm but the rads were still warming up, significantly more upstairs than down.

My pump, does this need to be set to speed 2 or 3 ideally?

Thanks

Slipperz

 

[bellairaphon]

If you leave the hw/ch turned off till the pipes go cold. Then turn the hw on which pipe gets warm first B or AB?

 

[slipperz]

If you leave the hw/ch turned off till the pipes go cold. Then turn the hw on which pipe gets warm first B or AB?

Ports B and AB both warm at the same rate.

This time when HW was selected PORT A was cold and B getting hot although the radiators were getting hot!!!

Now has the previous 3 port and now this 3 port been put in incorrectly??!!

PORT B goes straight into the cylinder and PORT A goes downstairs.

Do CH systems use the cylinder for expansion purposes? I hope it does then this is the fix!

Slipperz

 

[bellairaphon]

If you felt the bottom pipe in the cylinder does that become warm before the AB. It's starting to sound like a piping fault.

 

[bellairaphon]

No the 22mm above the pump is used for expansion.

 

[slipperz]

If you felt the bottom pipe in the cylinder does that become warm before the AB. It's starting to sound like a piping fault.

I think I may have sussed out whats going on....

The pipe from the bottom of the cylinder goes through a 22mm gate valve then Tees off 15mm to the radiators!!!!!! So if I shut this valve in it should sort the problem out??

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• slipperz
• 30 Sep 2013
• 1

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• slipperz
• 30 Sep 2013
• 1

22mm Gate valve from bottom of cylinder

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• slipperz
• 30 Sep 2013
• 1

Tee off from HW cylinder to rads

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• slipperz
• 30 Sep 2013
• 1

Overall pic of 3 port

Slipperz

 

[bellairaphon]

Yes the valve should off been put before the 3 port then linked to the boiler return. Even tho not needed. Shut it off snd it should be fine.

Nath

 

[slipperz]

Yes the valve should off been put before the 3 port then linked to the boiler return. Even tho not needed. Shut it off snd it should be fine.

Nath

Cheers Nath

I shut the valve and fired up HW again and the TEE that goes to the rad was getting red hot straight away.....Gate valve needs replacing?

Picture Title

• slipperz
• 30 Sep 2013
• 1

slipperz