Microbore problems

[gmac]

Hi all,

Having a bit of a problem with a microbore heating system, carried out a chemical flush, f3 added a week ago and returned to drain out and refill adding corrosion inhibitor, done all that and fired up the heating and checked radiators where heating ok, all but one heating 100%, the rad furthest from the pump, checked balancing and all l-s's fully open so shut all down to bare minimum and all but that one continue to heat fine.

Turned all radiators off except the one causing problems and as expected came upto temperature top and bottom of radiator, circulating fine, when turning other radiators back on the problem radiator started losing heat again.

The radiator in question is approx 16x69 dpc and 10mm run from 22mm drops, 10mm run approx 8-9m each way.

Any ideas

 

[CES]

Either a worn pump or could be a partial blockage in one of your pipes. Ive had that once and ended up draining down,removing the rad and fixing a foot pump to the end of the pipe and giving it a real good blow through on the flow and return.

 

[EPH]

Had similar on microbore and left the problem rad the only open for a week with system cleanser in and that shifted it.

 

[gmac]

The issue bein the jobs for letting agents, hence don't want to be spending any more than required lol
I've been thinking both suggestions, i.e ces worn pump and also eph - adding f3 again and circutaing the one rad, think i'll check pump first and then try the suggestion by eph if required, thanks guys

 

[EPH]

Wouldn't have thought pump if all the others are getting 100% hot like you say.

Whilst you're there bang some more cleanser in and give it a try over the weekend maybe.

Might be worth taking the rad in question off and give it a flush out with a hose too.

 

[diamondgas]

Just curious .. plastic or copper pipe? droppers from above by any chance? Open system by any chance?

Flushing microbore has its limitations I'm afraid and flushing generally gets rid of the suspended solids only not the caked on stuff!

Good luck! 🙂

 

[cdodds2004]

had sasme problem on microbore tried to clear with powerflushing and chemicals with no avail, ended running new pipe work to rad as microbore must of had a blockage was on 8mm in a bungalow and on open vented

 

[gmac]

Just curious .. plastic or copper pipe? droppers from above by any chance? Open system by any chance?

Flushing microbore has its limitations I'm afraid and flushing generally gets rid of the suspended solids only not the caked on stuff!

Good luck! 🙂

All copper, open vented as you say and 22mm f & r drops then 3 rads off the drops

 

[diamondgas]

You'd expect 3 rads to work no problem .... Generaly there's a design flaw that gives microbore a limited life span, IMO ... Active corrosion due to pumping over or surging ... doesn't help you out I'm affraid!

Instead of spending all that time flushing and back and forth, couls it not be more cost effective to repipe the troublesome rad? Just a thought!

 

[gmac]

You'd expect 3 rads to work no problem .... Generaly there's a design flaw that gives microbore a limited life span, IMO ... Active corrosion due to pumping over or surging ... doesn't help you out I'm affraid!

Instead of spending all that time flushing and back and forth, couls it not be more cost effective to repipe the troublesome rad? Just a thought!

You may just be onto something there but you know what landlords and letting agents are like, there is still a small amout of heat trickleing through when other rads are on and when other rad are off it heats perfect, do you think changing the 5m head pump to a 6m head might help.
as already stated all l-s's o other rads are literally closed as much as they can be.

 

[cdodds2004]

i would maybe try some fernox f5 left in system for a week or so its stronger than f3 and then flush again see if that shifts it, i really doubt the pump is at fault and even if the larger pump does get it to work i think it would stop in future, hiding the problem with a bigger pump imo

 

[SimonJohns]

what about balancing, it hasnt been mentioned yet but.
it worked with the rad being the only one on, and now the rest are open it doesnt?

 

[diamondgas]

You may just be onto something there but you know what landlords and letting agents are like, there is still a small amout of heat trickleing through when other rads are on and when other rad are off it heats perfect, do you think changing the 5m head pump to a 6m head might help.
as already stated all l-s's o other rads are literally closed as much as they can be.

Changing the pump to something more powerful tends to add to the overall problem to be honest!

Damage is done in my opinion!

A re-pipe might save the day and get you the money for the costly flush, rad not working, argument with the landlord! Weigh up the costs I guess and learn the lesson.. Honestly I have rarely seen a flush on microbore be successful!

 

[boblydon]

Powerflush it with hot water and sentinel jetflo (x800), had similar problems on many sytems, it's always the further radiator and usually on a dropper system.

Forget putting in a bigger pump, as Diamond say's that will only add to your problems with pumping over the feed and expansion tank.

Never yet had a job the power flusher has not cleared, remember flushing water must be hot and must use jetflo.

Hope that helps.

Bob

 

[CES]

As said, you are probably looking at a partial blockage, how you clear it depends on you really. I always check the pump as if its been running with crud in the system like that for a while the chances are it will be on the way out anyway.

 

[missplumb]

what about taking the radiator off and open each valve in turn to see what sort of flow you are getting.if one side is blocked and all the other rads are closed then it will still get hot giving a false impression. had one a few weeks ago on 10mm plastic drops. ended up the pipework was blocked but all the pipes were behind dot & dab walls. we just disconnected it in the manifold upstairs and attached the pressure tester to it, it took 20 bar before the blockage shifted - got there in the end.

 

[boblydon]

Bloody hell!!!!!! 20 bar pressure to shift a blockage????? 280psi in old money......what did you use to obtain 20bar????, cant imagine the fittings etc not giving way

 

[CES]

I wouldn't have liked to be disconnecting that bit of pipe! That would have made a "rather pleasant arrangement" on the wallpaper if not properly eased off! lol

 

[missplumb]

a rothenberger pressure tester. connectedto pipework upstairs and hose pipe to outside on the valve downstairs. i knew there would only be 1 or 2 fittings on the run so took the chance. the customer didnt want unsightly pipework in his lounge, even offered to box them in, nor did he want us to rip his walls to pieces to get to the blocked pipes. this seemed like our last option.

 

[diamondgas]

Sometimes needd must missplumb...lol

 

[missplumb]

well what can ya do, obviously informed the guy what could potentially happen and he was fine, even better when it worked:cheesy:

 

[tamz]

The biggest problem with microbore systems is asking them to do too much like heat an 1800k2 on the end of a 10m run. Open systems in general that may have been fine when installed were wrecked by someone changing a pump a few years later and leaving it on 3 because they knew no better.

To the op. Forget F3. You would be as well peeing in the tank than adding that. Use X800 or F5. Probably be cheaper to repipe than mess about with it unless you are on £5 an hour.

 

[gmac]

Thanks for the suggestions, Will try f5 as suggested, failing that will let landlord make the decision on next course of action, don't want to powerflush as the system is quite old and don't want to risk creating any more issues.

 

[cdodds2004]

fire some ds40 init that stuff is super strong but be very careful if you use as it needs neutralising and doesnt do the boiler seals much good if left in, thats why i usually go for f5 or x800 its still strong but a bit safer lol

 

[gmac]

fire some ds40 init that stuff is super strong but be very careful if you use as it needs neutralising and doesnt do the boiler seals much good if left in, thats why i usually go for f5 or x800 its still strong but a bit safer lol

Put the f5 in this afternoon, only circulating the one rad so hopefully gets it sorted, i'll find out on monday.