new radiator has got me beaten!

[chriselevate]

Any what this could be as I just can't get me head round it at all!

I've done quite a lot of reworking to my heating system but this last little bit has got me beaten and I can't work out what the problem is. The heating system (4 bed house) was working perfectly before I took a pair pair of drop down 15mm pipes (that fed 2 rads) and put them into 1 radiator in order to simplify a mess of pipes.

I've got the heating system running but it's not pushing the CH water right round the house, it's only hot around the boiler, pump and a few radiators near.

Have I perhaps hooked the new radiator onto 2 sends or 2 returns or something wrong? Any idea how I can test it? I've taken the radiator in question off the wall so is it best I connect up the two tails and see if that solves it? Or is it best to run them both into a bucket to see what the temperature drop/difference is?

Any ideas?
Really appreciate any help you can give. It's NOT a presurised system btw.

Thanks.

 

[BARNY78BG]

It's possibly air locked, put the radiator back on and turn off all the other radiators then turn the heating on only, don't turn hot water on, unless it's gravity fed hot water, then wait to see if the radiator comes on. If there is no heat then trace the pipes back to the main flow and returns under the floorboards to see if they tee into two separate pipes, oh yeah the rad is full of water and each valve open isn't it?

 

[chriselevate]

So... put the radiator in question back on and open up the trv and the lock shield and see if it gets hot? What if both are returns or both sends or is this impossible seeing as there are only 2 pipes that drop down?

When you say turn off all the others, do you mean just on the trv or do both sides need doing too?

Thanks

p.s. yes the rad was full of water and both valves were fully open.

 

[BARNY78BG]

As long as you have only used the two downpipes(flow & return) then there shouldn't be an issue with the flow to the rad, but yes turn on the culprit rad and turn all trv's off on the other rads, if they haven't got an off position then turn off the lock shields an wait

 

[chriselevate]

Is there a chance that the 2 drop downs aren't flow and returns or that there was something odd going on there by the previous owners? I mean if there are 2 pipes coming down (which there are) it would have to be a flow and return wouldn't it or not necessarily?

 

[BARNY78BG]

Did the two rads work off the pipes originally, if so then I can't see any issues other than an airlock which is quite common on your type of system after any drain down

 

[chriselevate]

Thanks Barny,

Yes it worked perfectly before I fitted the new one. I do know that after I filled the system back up and put the boiler on, the boiler got hot and after a couple of minutes it cut out. I went to the pump and gave it a tap with a spanner and it gargled lot's of air and started spinning better. I guess the pump might be on its way out or playing up too? I'll go and put that rad back on and isolate it to see what happens and then let you know.

Thanks.

 

[BARNY78BG]

Forgot to say, leave the boiler temp stat on low to avoid the boiler overheating while the air lock budges, ok

 

[chriselevate]

Ok. Boiler cut out after about 1minute. Rad is slightly warm. Boiler is gulping air and making a sloshing noise but is not ignited or fired up.

 

[BARNY78BG]

Just leave the system run as it is, depending on what boiler you have the pump should continue to run and push the airlock out, every 5 mins or so then reset the boiler and see if the rad warms

 

[chriselevate]

Ok... seem to be having a bit more success now. The one radiator seems to be behaving and getting nice and warm. Just to throw another annoying factor into the mix, I have 2 motorised valves near the pump so there's a possibility that these are messing things up too?!

 

[BARNY78BG]

Also if there are any bleed points around the boiler open them to let the air out, sounds like you haven't drained the system correctly

 

[chriselevate]

At the top of the boiler there are 2 x 22 pipe coming out of the boiler and one has a drain valve on it. I've opened that up and water flows.

What do you think I should do now?

When you say that I've probably not drained the system properly... what do you mean? I stopped the header tank filling (by tying it up) and opened up and a drain valve on one of my radiators down stairs. I'm guessing from what you said it's not as simple as that?

Thanks

 

[footprints]

By now your water in the system is full of air bubbles whisked up by the pump trying to clear it and just like brakes with air in the pump is just compressing the air not pushing water.

Leave it off overnight to settle and try it in the morning with luck you will get a great big gurgle and at least half the system will come on. Then turn off the working rads to push it around the non working ones.

 

[chriselevate]

I'm pretty sure the air is now out of the system. I actually wonder if the pump not working properly as I've only got 3 out of 15 radiators on at the moment and the ones furthest from the pump are only getting slightly warm. With it being off for a week and to get it to work today I had to give it a whack - does this suggest it isn't working correctly?

Thanks for your help