HELP- 3 heating engineers stumped!!

MY system is supposed to heat 15 radiators over 3 floors and has never been fantastic since we moved in but did manage to heat up at least half of the rads. Recently more of the rads stopped working and a plumber/ heating engineer suggested a block due to sludge.

He started by shutting off all rads then went round the house opening one at a time bleeding it and then running the pump at the highest then lowest and highest settings. This didn’t help so he put sludge remover into the system, drained the system then bled each rad . This stopped all of the rads working.

He suggested the pump or the 2 zone valve wasn’t working so we called in Brit Gas since they had installed the system.who replaced the front part of the pump and told us we needed a power flush and a new boiler.

3rd company, suggested one of the 2 port valves was stuck, when this was replaced they suggested the pump again. The system set up is as follows:
- Glow worm Hideaway 100B boiler
- Grunfoss Pump
- 1 Drayton 2 Zone Valve & 1 Appliance Components valve

We have piping hot hot water but no heating (only one of the upstairs rads get warm but not hot)

Before the flow pipe enters the Drayton valve, it has 1 branch pipe running to the top floor rads and another tap off for a bypass. When heating is switched on, the valve opens and hot water runs along the pipe for about 3 feet before it starts to get cold and within a few mins the entire pipe above the valve is cold- even though the valve is open. The top floor pipe gets warm but never piping hot. Another pipe coming from the H/W cylinder and running to the overflow on the roof gets piping hot almost immediately.

Sorry for the length of the post but I wanted to give as much info as possible. Also I’ve read most of the Q&As on the forum and tried a few of the suggested tips.
Thanks for any help you can give.

Easy. You need:
All air out of the system
Proper balancing
An automatic bypass
Valves which work
Properly sized pipes
Properly arranged pump and plumbing
Working radiator valves
No sludge - anywhere.

Chris, Thanks (I think!!), I figure that I'll have to put in some serious work to get things completely sorted but if I can even get things back to where they were until the weather gets better it would be a big step forward.

I've bled the system using the methods you and others like Allan have suggested, should this not get the air out of the system?

The valves are working as are the radiator valves, but don't I need heat in the radiators to balance?

can you gag the hot water circs down.

Fitz, sorry for ebing dumb, but don't know what gaging the hot water circs down is. can you explain?

can you stop the hot water side of the heating system so as to give priority to heating side only.

have you never wanted to gag your wife to shut her up.

In answer to your first question; haven't tried that, is it something I can do myself?
To number 2, can you imagine Christmas, cold weather, kids and a mum. Yep it has crossed my mind

Sounds like its blocked to me as seems to have been diagnosed on 2 of the 3 visits. That system cleaner tends to free up loads of debris from the system and then knacker the pump.

you cant add a sludge remover if its blocked. it cant circulate.

He put the sludge remover in when more than half of the radiators were working to try to clean out the bits it could reach. We've also had the pump off and the section that wasn't replaced was clogged a bit but that was cleaned out and it seems to be ok now.

sorry hit submit too early. If it is a blockage is a power flush the only way to clear? Only the BG guy seemed to think that would work and to be honest he was more interested in getting us to replace the boiler.

a full system flush can only help, and should enhance performance.

If it is a blockage is a power flush the only way to clear?

Click to expand...

Take off each affected radiator and run a gallon or two of water from each valve. That should prove that there is a route for the water to circulate to each rad and may help to clear any airlocks in the pipework.
Hard work I know but it will identify any problem pipe runs.

a powerflush does not clear a blockage.