potterton 28i combi more help please!!!!!

[giz123]

my boiler is still over pressureing checked expansion vessel and it is still at 1 bar. When c/h is running pressure gauge reads 3.5 + and vents any ideas

 

[ollski]

Drain the boiler, check the air pressure in the expansion vessel....should be about 1 bar, if not blow it up, if the fault occurs after this you will either need a new shraeder valve (easy) or a new expansion vessel (not).

 

[chrishutt]

blow it up

You may feel like doing this, but he means inflate with a bicycle pump.

Perhaps the connection between the expansion vessel and boiler circuit is blocked?

 

[giz123]

when you say drain the boiler do you mean competley drain the entire system or just drop system pressure

 

[gstens baxi]

Drain the boiler only ,this boiler has isolation valves (which do not leak when moved) and a drain cock inside the appliance under the pump. When boiler is empty check the pressure in the expansion vessel is 1Bar. When you say boiler is operational is it running heating or water.

 

[giz123]

it runs h/w ok it is just a problem with c/h

 

[Paul Barker]

That still signifies expansion vessel problems. Before you drain, undo bike valve (Schraeder valve) depress pin, if water comes out you have the answer, you need a new expansion vessel. Drain boiler and change it, new one should be charged to correct pressure, varies with manufacturer but usually about 1 bar.

If no water comes out may be deflated, pump up as advised.

If existing installation and nothing else changed we could be on right track.

If new installation on gymungus system you might need another expansion vessel in the system. Putting it on the return pipework near boiler makes it last longer, but check manufacturer's instructions.

Due to the problem the blow off valve may need cleaning/renewing.

 

[giz123]

no water coming out of valve ,but i am running a rather large system with 2 large victorian column radiators +6 others one of witch is rather large but system ran ok for about a year

 

[gstens baxi]

If it was the expansion vessel i would expect the problem to be evident on both heating & hot water. This could be due to a blocked return filter (if fitted by installer) wich should be fitted to the heating return isolation valve, the problem you describe could be due to the filter being in the wrong position (on the flow pipe) restricting flow to the heating circuit. It could also be due to poor circulation through system. Both of these problems will also see the boiler cutting out on temperature shortly after ignition.

 

[giz123]

boiler never cuts out just makes loads of churning noises(water) when it goes below 1bar on gauge

 

[chrishutt]

This could be due to a blocked return filter

Since the 28i has an automatic by-pass, I can't see how any restriction on the flow or return pipework could give rise to such high pressures (3.5 bar reported by poster) - unless the by-pass was itself blocked!

The evidence surely points to a problem with the expansion vessel or its connection, but the poster doesn't seem to be willing or able to be very systematic about testing it.

 

[giz123]

i'am afraid i dont really no what i' am doing when testing but have tested when system drained down and pumped up to 1bar seems better and running at just over 2.5 bar on presure gauge any tips on testing greatly accepted

 

[Agile]

When you have pumped the expansion vessel up to 1 Bar with the system open to the air, keep the air pressure guage on the vessel and repressurise the system to 1.5 Bar. See if the air pressure increases to 1.5 Bar as well.

If it does its fine, if not the pipe to the vessel is blocked as Chris suggested could be the problem ( and I suspect that too ! )

Always remove the filling loop when its not is use to comply with the water regs and to ensure that the filling valve is not leaking.

It is essential to do exactly what we tell you as otherwise you are not testing what we have asked. You may have your own ideas but as they have not fixed the problem it would be much better to follow our advice as we fix heating systems all the time!

Tony Glazier

 

[giz123]

yes pressure does rise when i recharge system ,i may sound like a bit of a **** but i cannot find a drain on the bottom of the pump and have been draining down by operating pressure relief valve is that ok .(i really am all at sea with boilers )

 

[gazthepottertonengineer]

yes pressure does rise when i recharge system ,i may sound like a bit of a **** but i cannot find a drain on the bottom of the pump and have been draining down by operating pressure relief valve is that ok .(i really am all at sea with boilers )

yes it is ok to do this but check aftyer you have filled up that the prv isnt letting bye as this often happens also drain off is just below pump to the right but you need to take case off to see it, it has a white knob which you need to turn to open it