Circulation failure in central heating

[humiteyubee]

Hi, please help,

My ageing Myson Marathon boiler in my open vent system seems to be generating plenty of heat. The boiler inlet and outlets are very hot as is the pump. The two way honeywell valve activates. I have tried a mains flush and a bucket flush at all the rads and all seems fine. I attached a flexi pipe and bucket to an upstairs radiator and after drawing off a couple of gallons I get good heat to the downstairs radiators. Pump is fine.
Last week I tried Sentinal x800 but still have poor circulation. Advice would be very welcome.

C

 

[dcawkwell]

New pump.

How do you know the pump is fine?

 

[humiteyubee]

The old pump seemed fine but I put a new Flomasta pump on just in case but no change.

 

[dcawkwell]

The old pump seemed fine but I put a new Flomasta pump on just in case but no change.

There is a blockage somewhere in the system if you are getting no circulation. Perhaps an air lock. Close all radiators except nearest one. Does it get hot? Close that one and move around in turn.

 

[humiteyubee]

Thanks. Have been down that road before but worth another shot.
I'm thinking ultimately that I will need a pwerflush

 

[dcawkwell]

Thanks. Have been down that road before but worth another shot.
I'm thinking ultimately that I will need a pwerflush

Not a fan of power flush myself. But using a hose pipe and the mains cold cshould sort it out.

 

[humiteyubee]

Have tried a mains flush including a mains flush through the pump bottle valve and off of a couple of rads but again no joy. I think I may have to hire a powerflush unit and attach to the pump valves (having isolated the header tank). Something will work eventually.

 

[dcawkwell]

Have tried a mains flush including a mains flush through the pump bottle valve and off of a couple of rads but again no joy. I think I may have to hire a powerflush unit and attach to the pump valves (having isolated the header tank). Something will work eventually.

Mains flush will clean a system better than any power flush. The force is much better. Hiring a powerflush machine will just be a waste of money.

What is the results of just having one radiator open and boiler on.
Does each radiator in turn get hot?

Does boiler flush through ok.
I would disconnect a radiator attach hose on flow of radiator pipe and flush through to return of radiator pipe. With all other radiators off. If this is working it must be ok!

 

[humiteyubee]

Tried individual radiators but no noticeable flow from the pump. The only heat I can circulate is by draining three gallons or so from a rad. Could this be an isolator valve stuck closed but allowing some flow when I do my rad drain off?

To do the mains flush through a rad as you suggest I expect I'll need to cap off the header tank flow and vent?

Many Thanks

 

[humiteyubee]

Found a couple of air release valves on pipes going up into the loft and back down to feed two bedroom rads. Fiddling with these released air but did not help with the circluation. I also capped the feed from the FE tank and connected the cold feed direct to the FE vent pipe and gave some good blasts of cold feed but still nothing. I finally coonected cold main direct to landing rad and gave that a blast, again no circulation.

I can get all the rads hot but draining off about 3gallons from the landing rad.

Any further suggestions helpful but think I might need to replace the 2 port valve for the CH.

Many Thanks