Circulation Problems

[fatboy123]

It’s a system boiler with an open vented system, with a domestic hot water cylinder.
I inherited this plumbing job from somebody else who got chucked off site. There was an existing boiler, tanks in roof and domestic hot water storage cylinder. All radiator pipework was changed by the other plumber, and all I have done is fit the radiators to the wall.

I filled the system up and could only get hot water flowing around a couple of the radiators upstairs. I then tried filling the system from the drain off point of the radiator, and reverse filled it all the way back up through, hoping to clear the air. I then checked the mid position diverter valve which is all working. After a lot of perseverance I can now get all the radiators upstairs working but none downstairs.

Any ideas of what else I could try?

 

[Keefy]

Try turning off the (hot) upstairs rads then check if the heat is forced around the rest of the system. Also, just a thought - as I've discovered the same problem was caused by this a few times; check to see if the downstairs rads are all fed from a single 15mm drop tee'd off a 22mm, if the pump is set too high it can 'shoot past' that drop.

Edit: Can 'shoot past' if the drop is tee'd off going more or less straight down. Replacing that bit with a 45 degree bend might help. That's what I've found to be the cause before.

Any idea why the other fella got kicked off the job? Maybe there's a slight chance you'll find the answer to the problem lies with that reason.

 

[Best]

As above, - turn upstairs rads off, if you haven't already. The pump should circulate to downstairs no matter how it's piped, so if it still doesn't work you have a faulty pump or a blockage of dirt or air. I would try the easier things first. Some pumps only work partially & heat first few rads or upstairs, so don't rule that out. If you think it is a blockage you could try turning all rads & pipes to cylinder off & connect to one side of a downstairs rad valve from the mains with a hose & see if it go to feed & expansion for a second. Then try other side of rad. If they are clear, you have a pump problem.

 

[fatboy123]

Thanks for your advice. Still having problems after 2 people spent a day venting all the radiators and trying to get air out of the full system. We fitted a new mid port valve and put in a new pump, and we had the whole system all working when we left that day.

The boiler was then switched off and the next day when it came on only the radiators upstairs worked and none downstairs heated up. The feed pipework to the TRVs downstairs are hot on all Rads but there doesn’t seem to be any flow through them. The only thing I can think of now is to fit an air vent on pipework to get the air out. Any other ideas??

It is an open vented Y plan system.

 

[acecharly]

Have you tried removing the TRV heads?

 

[Best]

Join the mains water with a hose & jubilee clips, to a rad valve on one of the rads that isn't working & give it a few seconds only. Then do the valve on other side of rad.

 

[fatboy123]

Join the mains water with a hose & jubilee clips, to a rad valve on one of the rads that isn't working & give it a few seconds only. Then do the valve on other side of rad.

yeah allreally done that ?