Heeeeeeeeeeeeeeeeeeelp!!!!!!!!!!

[jase158]

Power flushed a system today,

upstair 15mm, down stairs 10mm, problem = downstairs radiators cold/ luke warm.

I power flushed system, used boiler to heat water as per usual, all radiators got warm,

finnished power flush, and went to fire up, still not heating fully, couldn't get circulation, so tried removing air locks no joy, replaced pump, got all radiators working but no better then originally.

took 3 radiators off and flushed with a hose, water was absolutely black.

1 rad valve was leaking so had to drain down when doing this,

put radiators back, refilled and nothing.

went round and opened 1 rad at a time and got heat to each rad, turned them all on and same problem again.
Really at a lose at what it could be now, probably something simple but I started at 8am, left at 11.30pm

ahhhhhhhhhhhhhhhh

thank you in advance

 

[PlumbBobBob]

possibly a blockage in the microbore shown up by the black water which shouldn't have been left in the system after flushing

 

[jase158]

bit confused what you are saying, but water was running clear when i finnished, but absolutely cold spots on bottom of rads

 

[PlumbBobBob]

i'm saying there is a blockage which meant that the flush wasn't as thorough as you thought it was, hence the black water.

 

[Best]

Got to be a blockage still, as you also changed the pump. Did you put a chemical in just when flushing? I think it is better to use a chemical that is supposed to be in the system for a week or more, before flushing.
Some systems are not going to be fixed by a few hours power flush surely.

 

[jase158]

and how do i clear the blockage?

 

[jase158]

apparently customer had chemicals in for 2-3 months

 

[PlumbBobBob]

maybe the chemicals just moved the sludge about until it came to the microbore.

 

[jase158]

would flushing from the rads help?

 

[Best]

and how do i clear the blockage?

Tempting to risk putting mains through each individual rad pipe from one set of flow & returns.
You could try a longer term chemical & leave to work, or do a blockage clearing chemical ( think Fernox do one) which have to be removed / neutralised in a few hours. No certainty though.
Probably stating obvious, but make sure the 10mm circuits have full flow - system balanced & copper tank, if any, balancing valve well turned down, & that circulating pump is at least 6m head.

 

[Best]

would flushing from the rads help?

I would think flushing from a large pipe, 15mm or more, towards each 10 mm pipe worth doing. Even just using mains carefully.
Maybe the chemicals were left too long? You might have to start from scratch.

 

[Mike Jackson]

I've had a job like this. Spent about 4 hours flushing but couldn't get the heat through to a couple of the rads. I removed the rads and flushed them through outside, got loads more muck out of them. I then capped the cold feed and open vent again. To avoid pushing and muck back into the boiler I took out the pump and connected a hose to the pump gate valve and connected a hose to the drain off on the heating return in the airing cupboard. I left both of these fully open and gently back flushed with mains water from the radiator valves. I couldn't believe the muck that came out, it looked like tea leaves, it's no wonder the rad wasn't getting hot.

 

[Nostrum]

Powerflush machine and 10mm, there's your problem. All that muck that you've dislodged has now found a new home in the 10mm or manifold. Personally I don't powerflush microbore for that reason. I would drain down and take the manifold out, get it in a bucket of water and make sure all the ports/connections are clear. Then start working your way through the 10mm to make sure they are clear one by one.

Sometimes brute force isn't the best solution.

 

[jase158]

thanks for all the advice, just out of curiosity, is there any other things that could be causing radiators to not warm up, that I haven't thought of,

like manifolds not used, but 15mm/10mm/ 15mm reducing tees instead.

downstairs circuit on hot water circuit, rather then heating circuit?

I think it would be a very hard thing to prove as pipes are under the floor but any suggestions please.

Also can anybody tell me the difference in pump head? why woul you need 6M head pump instead of 5M head pump?
how do i work out size needed?

Thank you

 

[Nostrum]

Just re-read your original post.

Have you balanced the system up after the powerflush, you'll have to throttle the 15mm rad's back some way to persuade the water to flow through the 10mm properly. If your getting each one hot on its own then at least you've proved you have circulation so ignore my above post.

Sounds like a balancing issue to me, turn all the 15mm's off and try and concentrate on the 10mm's, once they are all getting hot 1/4 turn at a time on the 15mm's until they are all working.

 

[Mike Jackson]

Go to Grundfos UK and you'll find all the information you need there for pump sizing.

 

[Best]

A 6 metre head pump on a small house is better at pumping around a system that has microbore pipes &/or some restrictive designer rads, even though a 5m
head pump could be the correct kw output rating.
You may obviously need higher flow pump on larger than average homes.
I think the 6m head have more torque, so maintain flow rates.
The pump performance is extremely important on microbore, check pumps not clogged & don't assume a new or fairly new clean inside pump is working properly, as they often can be only partly working. Have just changed a brand new pump that would only put heat to downstairs if upstairs rads off!
Check with pump specs if in doubt as someone said.

 

[jase158]

Definetly not balancing issue as I turned all the rads off upstairs and downstairs still not getting hot, tried turning all off except one downstairs still not getting very hot, tried doing this to every single rad and still nothing, I definetly think it is a blockage, like said before, or air possibly. But worse case scenario, possibly a design fault. but cant see any possibility of this.

 

[jase158]

thanks to everyone who posted.

went back today, took each of the downstairs rads off, powerflushed outside,

checked for flow on each valve, still not getting hot.

then in a moment of greatness i suddenly thought about the H bit (not sure of proper name for it)

took this apart and it was so blocked that it was near to the size of 15mm pipe. changed this and it all worked, beautifully.

Thanks again guys

will add photo if it lets me.

 

[jase158]

here it is, the Whole of the H shape was exactlt the same covered in sludge.
Thank you guys

 

[LeakFinder's]

I hate microbore it is only good for oil lines and brake lines on cars. I find idiots still installing it on new builds today. The sooner that rubbish is banned the better.