Radiator problems - calling all you plumbers

CuteOne

I am in a new house with OFCH and a sealed system. Rads are Stelrad. My downstairs radiators are heating properly but I am having trouble with the upstairs ones. It is a zoned system and I have the switches for both zones (upstairs and downstairs) on. I have been reading some of the other posts and have read about the prssure guages. I don't seem to have one, as far as I can tell. There are 5 radiators upstairs. 2 have worked properly at times and when I have bled them some air was released and then water dripped out as expected. Of the other 3, 1 heats up to some degree but the other two seem to be dry. No air or water comes out when I bleed them. There has been some heat in them, the bottle of the radiator and sometimes up to 3 quarters of the way up gets fairly warm or hot. How can that be if there appears to be no water in the rads? Both sides of the radiators are on. It is doing my head in. I know I will have to get a plumber. I am just trying to understand what the problem might be. Also, the 2 upstairs rads that have worked properly can be temperamental, sometimes heating fully and water coming out when bled, sometimes heating but no water coming out when bled!! Please enlighten me.

Pete67

Sounds like you heating system is low on water. Without adequate pressure in the system opening the vents on upstairs radiators will not release either air or water, and may even pull air into the system.

When venting radiators on a sealed system the system pressure will drop, and water must be added to make it back up. There is usually a pressure gauge fitted for this purpose, which is essential if filled from the mains to avoid over filling the system.

You will need to find how the system is filled, usually from the mains water supply but sometimes from a roof tank via an isolating valve and check (one-way) valve. If it's mains filled, there may also be a pressure reducing valve fitted. If you post up some pictures of the piping layout in the hot press, and at the boiler it will be easier to advise further.

CuteOne

Thanks. I'll take some pictures in the morning and post them up. If you get a chance to look and them and advise me further that would be great. It's doing my head in and I'm determined to figure it out, with help : )

GopErthike

Don't stress, its not a big problem. As Pete67 said its definitely a water level problem and should be easily rectified. Because its a new house there is probably a filling loop somewhere, usually the hotpress. (its often a silver flexible hose with a white valve). you need to top up the pressure with this. Just in addition to what pete67 said, when you have it topped up and fully vented, i would isolate the downstairs rads and just let the upstairs run on their own for an hour or so. this should move any more air from the pipework to the rads and improve the circulation.

Hope this helps.

CuteOne

Right, I still can't get pics until the morning but I've been looking in the hotpress again. There is one white pipe with a red wheel on it and the plumber has a little labelled keyring hanging off it with 'cold water into heating system' written on it. He has a lever on another pipe labelled 'cold water shut off'. Do I need to turn the wheel to let more water into the system? I haven't touched anything!

GopErthike

'cold water into heating system' ...... is the valve you need. but you really need to see the pressure. there should be a gauge somewhere on the system, maybe attached to the safety valve at the boiler? If you fill it without knowing the pressure, most likely it will go too high. 1 bar pressure is perfect. But i wouldn't advise filling it until you find the gauge!

CuteOne

Ok, thanks. A friend of mine has a house in same estate but hers was built about 3 years ago. She has a gauge in hotpress near the red vessel thingy! I definitely do not have one in the hotpress, I've looked and looked. My burner and boiler are outside so I'll have a look there in the morning to see if I can locate the gauge. Thanks for your advice so far. I'm one of those with a curious mind who isn't just happy to hand it over to someone else without wondering why first and trying to get to the bottom of it! I needs to know why things are the way they are! More of a curse than a blessing at this hour!

JamesM

If you do not find the pressure gauge, turn the valve with the red wheel on for about 10 seconds, then close it again, you will probably hear a rush of water. Then go the one of the rads that is not heating and bleed it. Some air will come out, then it will stop - close the vent - open the valve again - repeat etc. This might be a bit slow, but it will ensure that you do not overfill the system and build the pressure up too much.
Jim.

CuteOne

Thanks. Everything is starting to make a lot more sense now. One other thing though before I let more water in: I was doing a bit of research last night to find out what's what and was reading about the expansion vessel and its purpose. Then I realised that when my brother was having a look around yesterday evening he let air out of it. After having read about it, I'm pretty sure that was the wrong thing to do and it will need re-pressurising. My question is..can I still go ahead and let some more water into the system and bleed the radiators as planned or should I absolutely not and get someone to recharge the expansion vessel first?

Pete67

You need to recharge the expansion vessel first, a car tyre foot pump is ideal, or even a bicycle pump will do, but you need one with a pressure gauge. There is a small Schraeder valve on the top of the expansion vessel, same valve as used on a car tyre, just unscrew the cap, connect pump and pump it up to 1 bar. Do this BEFORE you add water to fill the system.

When adding water, increase pressure to just over 1 bar, vent a couple of radiators, this will casue the pressure to drop back again, go back and check/increase pressure by adding more water, and keep repeating until all radiators are full of water and the pressure is reading just over 1 bar on the gauge (once you find it).

If the pressure is dropping continuously then there is a leak somewhere which will need attention. It should hold for a month or more though, so check it monthly and top up to 1 bar if necessary. Always check the pressure before venting radiators so you don;t inadvertently let air INTO the system.