No Hot water in Unvented system

[Sjacobs]

Hi Guys

Made a bit of a cock up over the weekend.
I have an indirect unvented cylinder with a condenser boiler.
Wanted to change my radiator and valves in a bedroom for new. Turned off power to boiler, I shut water off at the stop cock, drained the central heating system down by the lowest drain point in my hallway with a length of hose to the drain.
Radiator and valves changed no problem.
When refilling up, by opening the stop cock and refilling the system I've now got no hot water from my taps. The pressure and flow is fine and on Saturday I switched to the back up immersion heater which worked fine.
The Worchester Ri boiler has power to it (blue light) but when called for hot water, the green light was either not there or on for a few seconds and goes. Can't hear anything happening but the boiler was getting warm.
Yesterday I opened the hot water taps, turned the stop cock closed, and then went the the Pressure Relief Valve next to the cylinder and turned it until water went through the tundish, opened stop cock and turned taps off as water returned.
What I failed to do was bleed of air in all my radiators at any point since refill.

My plan tonight is to close the stop cock, open the highest radiator bleed valve (in the bathroom) and drain the central heating system again via the drain valve in the hallway.
Then refill the system by opening the stop cock whilst I keep the bathroom radiator bleed valve open to push and expel any air up through this point, I'll also go to other radiators in between to bleed.
Should this work? Is there anything else I'm missing?

Sorry for the long post, just wanted to build the picture.

 

[ianmcd]

you shouldnt have to do all that ona sealed system,just keep the pressure up and bleed the rads one at a time, shouldnt really be affecting your HW though, when you say you dont have HW do you mean water comes out of the HW tap but is cold ? or do you mean no water comes out ? post pics of your cylinder and all controle thermostats etc and boiler

 

[Sjacobs]

Thanks Ian.

To be clear, I have got water but it's not hot at at all. I'm guessing because there is air on the central heating side and it's not going through the coil from the boiler.
I started bleeding the rads yesterday one by one but gave up after 30 mins as it just got to a pitiful nothing.
I will post pictures when I'm home later.

 

[Sjacobs]

you shouldnt have to do all that ona sealed system,just keep the pressure up and bleed the rads one at a time, shouldnt really be affecting your HW though, when you say you dont have HW do you mean water comes out of the HW tap but is cold ? or do you mean no water comes out ? post pics of your cylinder and all controle thermostats etc and boiler

Also what dko you mean by keep the pressure up?

 

[ianmcd]

Also what dko you mean by keep the pressure up?

That is why it got to a pitifull nothing, you will have a fillng loop somewhere, usually in the same location as the Unvented cylinder but not always, what boiler do you have ? some have the filling loop inbuilt, there will be a pressure guage either on the boiler or next to the external filling loop, this has to be constantly topped up as you bleed the rads, a lot easier if there is two of you doing it, one topping up the pressure as the other bleeds the rads, as said post pics so we can see what you have , is there a small red tank (expansion vessel) next to your unvented cylinder ?

 

[ianmcd]

sorry just noticed you have a Worcester Ri so you will have an external filling loop it is not on the boiler, also that boiler has a bleed point at the top of the heat exchanger that will possibly need bleeding , not always though

 

[Sjacobs]

sorry just noticed you have a Worcester Ri so you will have an external filling loop it is not on the boiler, also that boiler has a bleed point at the top of the heat exchanger that will possibly need bleeding , not always though

I can't see a filling loop by the boiler. I have an expansion valve external next to the unvented cylinder. However no pressure gauge on this. In fact I can't see one at all!!

Would there be a pressure gauge behind the boiler cover?

 

[ianmcd]

Would there be a pressure gauge behind the boiler cover?

No there is no pressure guage on your boiler, post pics of what is in beside the unvented when you get home

 

[Gasguru]

Surely this is a traditional vented heating system?
Why did you open the expansion valve on the cylinder pipework? It has nothing to do with the boiler circuit and you may find the valve will continue to drip once activated.
It sounds as though you just shut off the main stopcock and went ahead draining down the system.
Did you go up into the roof?

 

[Sjacobs]

Here is the photos of my setup.

The pressure relief valve is what I was opening yesterday. Do i keep doing this and the radiators?

 

[Gasguru]

You've got yourself very confused and are just causing more damage....
Do not touch any safety valves, they have nothing to do with the radiators.
Look at the tundish (the black item covered in scale) and if it continues to drip you will need to call in someone qualified to work on unvented cyclinders to replace the safety valve.
Turn the boiler off until the system is air free otherwise you will overheat it and potentially cause more problems.
Have a look in the roof for a small cistern and if you find it post the pictures back..I am not yet convinced you have a sealed/presurised system.

 

[Gasguru]

And just to add the tundish in picture 2 above is not compliant, there should be at least 300mm of vertical pipe below it.

 

[ianmcd]

It looks like you have an open vent system fed from an F&E tank in the loft, your problem could be an airlock or possibly when you drained everything you may have pulled sludge, into the system, causing a blockage

 

[Sjacobs]

You've got yourself very confused and are just causing more damage....
Do not touch any safety valves, they have nothing to do with the radiators.
Look at the tundish (the black item covered in scale) and if it continues to drip you will need to call in someone qualified to work on unvented cyclinders to replace the safety valve.
Turn the boiler off until the system is air free otherwise you will overheat it and potentially cause more problems.
Have a look in the roof for a small cistern and if you find it post the pictures back..I am not yet convinced you have a sealed/presurised system.

Hi. Thanks for the reply. Attached is a photo of the loft.
I didn't realise this was active and thought it had been decommissioned years ago and left because of the asbestos lining. (that's why we don't go near it) there is low level water in there and a ball float.

 

[Gasguru]

Is that really the feed and expansion cistern for the heating cistern..it looks too big.
Post a few more pictures showing the float and water level, there should only be a single pipe coming near the bottom.