Radiator and pressure problem

[Woody123]

Hi i wonder if anyone could give me some advice.
Im helping out my brother in law refurb his flat and have had problem after problem
Anyway, first problem was the water had been turned off for a couple of weeks and when i went to turn it back on the stopcock burst, fixed that problem but now when we have went to put radiators back on there is only 2 radiators coming on? i had all the valves closed when i was filling the system up and when i opened them one by one there was only 2 that let any air out and the other's dont seem to be filling up? Any suggestions?
Also i have noticed the expansion vessel rises to 4 bar pressure when the boiler was switched on which is obviously dangerous? What could the problem be any ideas?
He has a cold water storage tank that has been blocked in (which is wrong i know) and that sounds like it has a problem aswell as there is always a sound of dripping water?
Would really appreciate abit of advice here so if there is anything that springs to mind that i could be doing before calling a qualified plumber to come out and have a look?

 

[ajs heating]

i take it your still using a indiect cylinder for hot water, if you have a cold water storage tank.
what is the pressure when you have filled the system ?
what is the pressure when you start boiler up ?
does the pressure drop off when boiler turned off ?

 

[Woody123]

Hi ajs

Yeah it's a HW cylinder.
I have managed to sort the radiator problem out now and they are all filling up. I have bled them all so should be no air in the heating system now.
When i did this the pressure droped down to 1.5 bar which i assume is normal. However i though everything was fine until i switched the stopcock back on and as soon as i did the pressure in the expansion tank rose steadily to 4 bar.
It doesn't drop down until i let some water out of the system. do you think this could be the problem?
I can't say for sure but by the sounds of things the cold water storage tank is passing water from the float valve and could need adjusting? do you think it could be forcing too much water into the sytem thus creating the pressure build up?

 

[NickH]

Your heating system is seperate from your domestic water system. It sounds like the filling loop for the heating system has been left open and when you turn the stopcock on its adding water to the system. Check that the filling loop is turned off. The filling loop is a flexible tube, usually somewhere around the boiler or pressure vessel (big red cylinder), with a tap at one end, make sure its turned off.

 

[Woody123]

Nick mate you were completely right. the filling loop has been left open. i have closed this and now dont have any pressure increase in the expansion vessell. Cheers for that.
everything seems to be working ok now apart from when i switch the hot water and central heating on the boiler fires up and after a few minutes there is a red temperature light on the boiler comes on then the boiler switches off. We have hot water and the radiator in the bathroom is red hot but there is only one other radiator that is slightly warm. Do you think the system needs balancing? Or could this be a thermostat problem with the red light coming on? I wasn't present when all the radiators were taken off so dont know how many turns it took to turn them off.
p.s there is thermostatic radiator valves on all radiators.
Thanks

 

[NickH]

When you say you have hot water I'm guessing you have a combi boiler (instantaneous hot water). If thats the case then when you run the hot tap does the boiler fire up and continue to run while the hot tap is running. It sounds like your heating (radiator) system isn't circulating properly and the boiler is shutting off, does the pump run when the heating is turned on ? Also check that the rad valves are all open (both ends of the rad), thermo rad valves can stick shut so make sure they are open, take the heads off and you should see a brass pin sticking out of the top, this is sprung and you should be able to push it in with a screwdriver and it should spring out again (the open position). They may be seized closed, gently heating the valve with a blowtorch can often free them. If all the valves are open and the pump is running then you may have a load of air trapped somewhere and you will have to try to bleed it out.

 

[Woody123]

I will give that a try with the trv's nick.
No it's not a combi it's an indirect system i think with header tank and hw storage cylinder.
Just one more question (sound like columbo!)
could anyone explain what a primatic system is? someone has told me if i have this system and i try to drain it via the hot water cylinder then if there is alot of trapped air in the system then there is a possibility that this could crush the tank! This is oviously very worrying if i tried this as there is 100 litres of water in here! Is he winding me up or should i be concerned? is there any other way of draining the system?
My system consists of 1 big cold water header tank, hot water storage cylinder, little red expansion vessel close to the cylinder with a pressure gauge on it and a boiler and pump. Does this sound like a primatic system?

 

[ajs heating]

1. a primatic cylinder is not an indirect cylinder. it doesn't have a coil a
indirect does. check any label on the cylinder.

2. a primatic system can't be a sealed system. yours is it has a expansion
vessel.

3. and you can drain a primatic without it crushing because the cylinder
will vent out the vent pipe in the loft.
the only time you'll crush a primatic is if you bung the feed and vent
pipe and open a hot tap. so he's a muppet.

4. if your draining the heating system find a drain tap on one of the lowest
rads in the house.
if you use the drain tap on the cyl that only drains the hw not the
heating circuit.

 

[Woody123]

Thanks for your replies everyone sounds like better advice than i have received! i will try everything out 2morrow and hopefully all will be well. i will let you's know the outcome.