Central heating problem please help

[Sparks 2014]

Im new to the forum so would just like to say hello, Im not a plumber but I have a limited understanding of how most heating systems work.


I have just moved house and I'm having big problems with the radiators up stairs ,they are only getting hot half way up if I'm lucky.




Description of the system.
The system is a tank fed system, I have a big plastic header tank in the loft that is about 3.5m above the upstairs rads on the first floor of the house, a copper hot water cylinder in the airing cupboard in the bathroom cupboard on the first floor, the hot and cold water for the first floor showers and bathroom sinks is pumped from a stuart turner shower pump next to the hot water cylinder.
The boiler is a Valiant the central heating pump is a Grunfos there are 19 radiators on the system. I have contacted Valiant and Grunfos to ensure the boiler and the pump are the correct size for the system. which they are.
I am bleeding the rads nearly every day, I am getting air out of them but as time goes on I'm getting less and less air out of them. but they are still only getting hot about half way up, I can completely remove the bleed nipple and no water will come out of the rads. there just seems to be no pressure at all in the rads upstairs.
The rads will be quite old through out the house and all have TRV,s fitted, the only things that are new on the system are the boiler, central heating pump, magna clean & shower pump.


I would be so grateful if someone who actually knows what they are talking about could point me in the right direction as to what the problem is, I've had a few plumbers / heating engineers up to have a look and they don't seem to be able to come up with a solution.


Some say the header tank is not high enough to create enough pressure to fully pressurise the system, others say the it because the rads are old, I am quite sceptical about both answers.


I have checked that all the isolation valves are fully open throughout the system


Im pretty sure the house only has one heating circuit from what I can see of the pipe work, but again I'm no expert


I would appreciate it so much if someone out there knows what the problem could be


Thanks in advance
Karl.

 

[Dotty]

assume everyone's checked the vents aren't blocked?

 

[AWheating]

you only have one water tank either in the loft or above your water cylinder in the cupboard?

 

[Dotty]

And you only need to post once! not three times!

I've deleted the others.

 

[Dotty]

What model Vaillant?

 

[SimonG]

Pressure gauge on the boiler? Big red expansion vessel in airing cupboard? If no then its a problem with the cold feed.

Its magnet time, followed by some cut and shut, followed by a clean and finished off with a filter and some inhibitor.

 

[bright spark]

Have you tried venting with heating on or off. Some systems will only vent with the heating off.
Are you a 100% that it's not a sealed system.
another problem you might have is that your cold feed is blocked not allowing fresh water to come into your heating system.
you could get a plumber around to do a 'back fill'. Well that's what it's called in Ireland where ye attach a hose with mains water onto your system to fill it. Bit awkward maybe to do yourself, have to be careful you don't flood the place.

 

[stevetheplumber]

definitly try venting with the system of first see if the rads fill

 

[Chalked]

Looks like a sealed system to me.

is there a pressure gauge on the boiler fascia ? And can you find a filling loop? This may be close to the boiler, underneath or possible in the airing cupboard. It has two valves connected with a metal braded hose.

 

[happyflyer]

Sparks,

This might be a better all round getting to know what sort of system you have, how many plastic tanks have you in your roof space, one or two.

And secondly take a photo of the front of your boiler and post it please.

 

[Sparks 2014]

Thanks for the replies guys

I have tried to upload pic,s of the boiler and the cylinder cupboard, but it just keeps saying (Post denied. New posts are limited by number of URLs it may contain and checked if it doesn't contain forbidden words)

There are two tanks in the loft approx 500 litre each piped together, they refill with a ball cock, I think they also fill the hot water cylinder cause when the shower is being used you can hear the tanks in the loft refilling.


I have tried bleeding the rads with the system on and off, you seem to get less air out when the system is off.


One of the threads says (assume everyone's checked the vents aren't blocked?) where would I find the vents to check if they are blocked ?

 

[Sparks 2014]

Apparently the forum rules are I need to have posted 10 or more times before I can upload some images for you all to see. Which I find quite frustrating, but I suppose rules are rules.

 

[AWheating]

if your system is sealed you will need to put water into the system as you remove air out. If you message a moderator they may help you get your pictures up.

 

[mike76]

Put the filling loop on the mains water supply! Fill the rads! Unless the mains pressure is poor' just leave it on until the pressure builds up! Check boiler safety valve might be letting by and check exp vessel ! That seems to be a big system might need extra vessel!

 

[GRJA]

With rad key remove nipple then with a fine needle push through were the nipple as come from this will check to see if the vent is clear, TRV's you may have turned the valve on full but if the pin hasn't retracted will give a false impression that its open. Screw the head of from the valve NOT THE VALVE ITS SELF and see if the pin as retracted, gentle movement with pliers should help

 

[jonnyswamp]

Call a plumber/heating engineer in, he/she can tell you exactly what boiler and heating system you have and tell you how to operate it properly. Would also be a good idea to get it serviced, if you've recently moved in