Bleeding rads didn't work, do I need to repressurise CH?

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I've recently moved into a fairly new house. The problem is with two upstairs radiators, the bottom half is hot, top half is cold. I tried bleeding them but only a small amount of air came out of one and none at all out of the other. The pressure gauge on the boiler doesn't move off 0 bar, yet the HW system is absolutely fine and all other rads are fine too. Is this a fault with the gauge, or should I try to repressurise the system?
There is a flexible silver hose in the airing cupboard, from reading through this forum do I just need to open up the valve on that until the gauge moves to just under 1.0 bar and rebleed? Or could there be another problem I should investigate first?

Thanks in advance!
Matt
 
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Nearly, but search the forum for "filling loop" and "expansion vessel" and you should find lots of details.
 
Thanks again oilman. I'll take a look through.
 
OK, I've had a look through some of the posts turned up by the search and I just wanted to check something before deciding what to do. To fill up the system should I be using a filling loop by the boiler or the one by the hot water tank? It also seems that I should be checking the pressure in the expansion vessel, this is by the boiler also? Unfortunately access to the sealed system part of the boiler is blocked because the extractor tube from the cooker hood runs over the top of it, so I can't lift it up without distmantling that :rolleyes: .

There is a silver braided hose in the airing cupboard running from the mains water to the heating system, with a small screw-valve. Can I re-fill from this?

Thanks,
Matt
 
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With seeing your system, I can't advise which fliiing loop you should use. One thing you should do is disconnect the filling loops when not in use. Spectacular things can happen to expansion vessels if the filling loop valves leak.

One thing you will have to do is to dismantle the cooker hood to get to the expansion vessel, or you can fit an additional vessel somewhere you can get at it. If the first one goes then, it wont matter. You can never have too much expansion space. But you need to know the air pressure in the expansion vessel.
 
If it helps the boiler is an Ideal Classic FF240. The hot water tank is a Megaflo. The hose in the airing cupboard has a little tag on it saying "Filling Loop: Disconnect when not in use". I presumed the screw valve prevented any unwanted flow to and from the main supply. I have a digital camera so could post pictures if required.

If I get nowhere with it myself I'll probably get it looked at when I get the system serviced.

Thanks for your help oilman!
 
When you bled the radiators did you get water coming out to prove the radiators were free from air. If you did, then there is something preventing the flow of water. blocked or partially closed valves maybe.
I would certainly be opening the valves fully to see what effect there is.
I would also seek confirmation the bleed valves are not blocked.
The fact your pressure was down should in my opinion not prevent you from bleeding the radiators.
Bleeding the radiators will of course release/reduce the pressure.
:rolleyes: :rolleyes: :rolleyes:
 
The Megaflow is an unvented cylinder and has an expansion space inside. Th space gradually reduces as the air is absorbed. It can be regenerated by following the instructions in the Megaflow manual. If you haven't got one, get in touch with the manufacturer.

Unvented cylinders should be serviced annually. This should be done by a certificated operator, and make sure you see their card. It is illegal for anyone else to do it.
 
No water came out the radiators, hence me thinking that the pressure was down in the CH system. I've regenerated the expansion gap in the tank, which seems to have fixed the other problem I had (drip from pipe outside).
I do already have a full set of user guides for every part of the system, which has helped me to understand it a lot more.

Apart from two radiators only being half hot everything else is fine, both CH and HW. To be honest though I don't know if the system has been ever serviced and it is nearly four years old now. I will have a look around for a certified Megaflo operator and get it serviced ASAP.

Thanks everyone!
 
Hi this is for Oilman,

We have a 3 bedroom semi house, we have a combi boiler 24kw, we also have 10 radiators.

We were thing of upgrading the boiler to some thing higher than 24KW.

The water low of our system is very high.

What will be your recommendation.


Many Thanks
 
This is hyjacking the thread really. It would give you more info if you started a new topic for this.

Does your system work? or do you have problems? If things are ok I wouldn't recommend spending money except on having it propery maintained. Is it oil or gas fired? Why do you need more than 24kW? boilers should be the right size, not oversize.
 
MattH,
4 years old is old enough to have problems with an expansion vessel, if you can't check the air pressure, it's worth getting it done (though at the moment you will be using the two radiators as expansion space).
 
MattH
Yes you do need to pfill your heating system. Open the valve on the boiler filling loop and the pressure gauge should rise. If it doesn't it's the wrong loop..! As you said 1 bar is ok to set it to.Then you should be able to get air out of the radiators. This will drop the pressure so you will haveto refill it.
If you are getting a lot of air collecting in your radiators it's a sign of corrosion. I'd empty the system (may have soldering flux left in it) and refill, with inhibitor added.
 
I contacted Heatrae Sadia and they gave me the number of a heating engineer certified to work on Megaflo units. I'll give them a call on Monday and speak to them.
One last question, would the big companies like British Gas have engineers with the necessary certification to work on sealed systems? Would like to get a comparison of quotes and what work they would carry out.
 

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