Replacing a 3 port valve

[Jever]

Unfortunately, there is no end of crud in the f/e tank and it didn't occur to me to clean it out before starting work.

I haven't got a magnet (but will try to get one) and I'm not sure if I can find where the cold feed tees into the flow pipe from the boiler, (probably behind kitchen units).

However, assuming you're right, what would be the solution? Drain down again and open up the system where the blockage is?

TIA

Jever

 

[Armo74]

The cold feed may tee in the flow pipe in the airing cupboard before the pump and near the vent pipe.
Bearing in mind I'm not there so my suggestion is only something you can check, it's not necessarily whats wrong.
If there is a blockage it will need cutting out and re-piping.

 

[Hugh Jaleak]

20degs movement is about par for the course on Honeywell valves. They use a rubber ball on an 'arm' that travels between the two outlet ports to block/allow flow as required.

 

[Jever]

Hi,

I've been up in the loft and traced the out feed from the FE tank down to the airing cupboard. Assuming I was successful in attaching the photo, it's the 15mm pipe between the 2 22mm pipes with the red stopcock that then goes on down to the pump (with the strange feed from the right - what is that weird cylinder thing?).

I unscrewed the magnetic knife rack in the kitchen and tried it against the pipes, but there was no sign of attraction (it's a pretty strong magnet as well). Nonetheless, the blockage could quite easily be non-ferrous, couldn't it?

My thoughts now are to drain down again and dismantle as much of the feed pipe in the airing cupboard as I can to identify any unwanted bodies.

Would this be a good idea?

TIA

Jever[/img]

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• Jever
• 15 Nov 2013
• 1

 

[jackthom]

If this airing cupboard is upstairs then at least the system won't need much draining down before the bottom of the gate valve can be safely undone.

Then it should be fairly easy to check and flush out the section above.

 

[footprints]

The cylinder thing is an air separator it is just an empty vessel that configures the open vent and heating pipes correctly, the theory is that the water flowing through it swirls around like a whirlpool and helps air to escape up the open vent. That and in particular where the 15mm cold feed tees in is the most common place for a blockage to form, black sludge can turn into something resembling concrete in there!

I have never got the magnet idea to work but it is always worth a try as a check. Strictly speaking there should not be a valve on the cold feed.
If you want to start looking out for blockages the starting point would be undo the unions on the gate valve and pump and cut out the other pipes on a straight bit to allow for a compression socket to reconnect.

 

[misterdubya]

The blockage (if there is one) will most likely be where the 15mm cold feed pipe meets the 28mm flow pipe. Its a shame there is a pulled set on the cold feed, otherwise you could just turn off the gate valve, undo the bottom connection, push a long screwdriver down the cold feed and clear the blockage that way. (I'm making an assumption that the system didn't fill after you replaced the valve - you may need to drain a bit off if it did partially fill). You will push the blockage towards the pump though.

EDIT: as per footprints!

 

[Jever]

I can't quite believe this. I was staring at the airing cupboard thinking where to cut first, when I thought I'd close the stopcock on the FE feed before draining down and opening up the pipes.

The surprise was that the stopcock was already closed and I have no recollection of closing it yesterday when I replaced the 3 port valve.

Anyway, a lot of glugging followed and now all of the downstairs and upstairs radiators are full and bled.

However, although the boiler fired up this morning for a while, it's not firing up now. Is it possible I've damaged the pump by switching on with the stopcock closed?

Would be grateful for any guidance.

Jever

 

[Agile]

You might have damaged it by using it without water.

The strictly no valve is only to prevent idiots turning off the valve and then to have no water to feed into a boiler which is stuck on and firing constantly.

The constant flow of water allows the boiler to boil it off and remain safe(ish).

Tony

 

[footprints]

If it is damaged it usually rattles, as the bearings will have gone you can check if it is seized by unscrewing the plastic knob on the pump pulling it out and spinning the pump by hand.
Even if the pump is knackered the boiler should fire for a short while.

If the boiler is not lighting at all now it may have tripped an overheat stat is there any reset button on the control panel?

Has the pilot light (if it has one) simply gone out?

 

[Jever]

Hi,

I don't think there's a problem with the pump, it whirs quietly when I switch the heating on.

The boiler is an oil fired Myson Velaire, approaching 30 years of service.

There is a red reset button (see picture), although pressing it doesn't produce any results.

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• Jever
• 15 Nov 2013
• 1

However, looking at the instructions, (see following scan, high limit thermostat section), there appears to be an additional high limit reset.

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• Jever
• 15 Nov 2013
• 1

I found it on the boiler (see following pic), but the black or green plunger no longer seems to be with us.

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• Jever
• 15 Nov 2013
• 1

I tried to press what remains of the reset (appears to connect to a thermocouple), but got no results.

Is there a way out of this, or should I consult the guy that services the boiler?

TIA

Jever

 

[footprints]

Afraid the only oil heaters I have ever dealt with you poured in paraffin and lit the wick!
That reset button does not look too clever, looks like it has had a lot of use, as long as you are sure the system is now full I think I would call in the expert