Cold downstairs rads, hot upstairs dont know how to fix problem, HELP!!!

[mubz]

Hi there guys, completely new to this site, have had a problem recently on my heating system. Have read a few threads and most of you guys know what you are doing.

Problem started a week ago, where my downstairs rads stopped getting hot, the upstairs are working completely fine as is the hot water.
The system is a gravity fed system. I have read a few threads and tried diagnosing the problem, but to no avail.

I have drained the system and replaced the honeywell zone valve for downstairs, checked the thermostats are working by turning it down and up and checking if the valves do the same. I have also replaced the old euramo gold pump with a new grundfos alpha 2l 15/50 pump. After replacing the pump one heater worked downstairs and another warm, however there are three still stone cold, I have tried bleeding them thinking its air but they are full of water.

I have just spent a lot of money but nothing that major better, could you please give me some advice as to what it could be, or I can do to remedy the problem.

Many thanks in advance

 

[BuilderMCR]

Try closing the upstairs lockshields if the downstairs rads get hot then your rads need balancing

 

[buckley plumb]

as above turn off all the upstairs radiators to see if the down stairs get hot.

 

[bewsh]

is the pump on the right setting? seen a few of these new grundfos pumps on auto and giving problems.

 

[JCplumb]

You say it's a gravity system but you changed the pump.
I'm guessing you mean it's an open vent system.
As above - try turning the upstairs rads off to see if downstairs get hot. Also worth getting a strong magnet on the pipework where it tees off for the feed and expansion, also check the tees where the upstairs pipework meets the downstairs pipework, and the elbows at the bottom of that run.. If it sticks you have a blockage that will need cutting out.
Check that the relevant port valve(s) is(are) working properly, I know you have changed them but that doesn't rule out a wiring issue.

 

[StillLearnin]

Have you checked the obvious .... rad valves at both ends turned on .... caught me out before. Unlikely to be the problem by the sound of it but worth checking. Would help to know the outcome of turning the upstairs rads off.... did it make a difference?

 

[mubz]

cheers for your quick replies guys,
I have two thermostats one for upstairs and another downstairs, i turned the upstairs completley down to shut off the valve for the upstairs rads the same happens downstairs, a few get hot while others are still cold. would this rule out the balancing?

I have got the pump at the full constant lll setting.

Jc plumb sorry yes i have the open vent system, i have read up on the magnet trick but most of the piping runs under the floor boards so i couldnt ger very far. I assumed as seen as tho the pipes are getting hot either side of the valves there isnt a blockage here, am i right in thinking this?
thanks

 

[mubz]

just to mention the heating system hasnt been touched for a long time before this problem, so all the radiator valve are as they as before, all open.

 

[stevetheplumber]

Probably its the pump ,does it feel hot? upstairs rads and heating will run on gravity

 

[BuilderMCR]

Try the magnet trick

 

[mubz]

I have just fitted a new pump today, yes its hot

 

[GasmanxxxR1]

go to each upstairs rad and turn it off, check if any got hot downstairs, if only one or two do then turn them off and see what happens

 

[stevetheplumber]

if you have two thermostats there will be two motorised valves sound like the down stairs one isnt working

 

[mitchellcook]

Hi mubz. You say the rad valves are open on the problem rads. Are they TRV's. If they are unscrew the heads and see if the pin is sticking up or if it is siezed down. This is a fairly common problem especially when you said it's an old system. Mitchell

 

[JCplumb]

Jc plumb sorry yes i have the open vent system, i have read up on the magnet trick but most of the piping runs under the floor boards so i couldnt ger very far. I assumed as seen as tho the pipes are getting hot either side of the valves there isnt a blockage here, am i right in thinking this?
thanks

Not necessarily, they could be getting hot through conduction, we want convection and ultimately radiation. Woohoo i got all 3 heat transfer types into one sentence!!!
Go round and turn off each hot rad, then when your couple of downstairs ones get hot - turn them off. Do any of the cold rads now get hot?

 

[mubz]

cheers guys i think it was the balancing, all working perfectly now, all toasty:93: lol, surprising overlooking a simple task can have such an effect on the system. thanks alot all of u guys