Hot water from boiler not reaching pump

[gas4you]

Softus, the only point I disagree on is the gate valve in the cold feed. This is usually standard practice, but obviously has to be left fully open.

From looking at the photo I would say the entire system is piped incorrectly

The flow from the boiler should rise above the valve then t across about 150mm, with the open vent going up off this t, then a t down to the pump, with the cold feed joining on the top of this t forming an h section.

The pump should be next, then the auto bypass valve, then the 3 port valve. From the looks of this the only time you have a working open vent is when the DHW is being heated

I think some serious re-piping needs doing here

 

[Softus]

According to what you've found, you have water in all the right places, and all relevant valves are open.

If this the case then you wouldn't have a problem, so unless the boiler is air locked then I'll wager (a rare thing for me) that one of your assumptions is wrong. You need to revisit every conclusion you've reached and challenge it.

One common problem in heating systems is the cold feed blocking. Do you get a lot of water and/or air from the highest rad vent in the system? If not, then you have a blockage.

 

[EliteHeat]

In the interests of getting the heating on until such time as this horrible mess of an installation is sorted out ( ) why not just manually open the 3PV, stuff a hose down the open vent and see if you can drive the water up the return?

 

[EliteHeat]

I think some serious re-piping needs doing here

I don't think anyone would disagree with you on this one!

 

[Gasguru]

I scrap the current pipework arrangement (it dosn't allow proper venting)and go for a close coupled feed and vent in a conventional H pattern.

Also stick a seperate air vent off an upstand on the cylinder primary feed.

Loose the gate valve on the feed. Older boilers must be allowed to boil the water in the event of a thermostat failure so require a guaranteed water feed.

Bin those leaky pump valves and get some quality gate valves on there.

 

[Softus]

Softus, the only point I disagree on is the gate valve in the cold feed. This is usually standard practice, but obviously has to be left fully open.

We can debate that one another time.

From the looks of this the only time you have a working open vent is when the DHW is being heated.

B*gger it. I stared at that vent for ages, feeling that something was wrong, and missing the obvious. I am a tit.

I think some serious re-piping needs doing here

Like this?

 

[gas4you]

 

[bobthebender]

[quote I am a tit.
quote]

Yep.

 

[Doallyn]

thanks for all the replies!!!

yeah its a mess, it really is - the previous owner was a builder who did the place up from a shell about 10 years ago - and now we've got it everything is falling apart!

the plumber who came round to fit the cylinder didn't say anything about the pipework being incorrect (it was after all working before hand) so i can't see why it isn't working now, literally all that has changed is the Pump, 3valve and the cylinder

there is a little air vent valve coming off the top cylinder pipe from the 3port which has water in it!

arrrrrgh!