Flushing central heating

[WotEver]

Not boat related but I figured someone on here is likely to know the answer. We have 10mm microbore central heating pipes at home and have had successions of blockages with random radiators not working. BG are coming on the 17th to do a Power Flush, which will be their third Power Flush over the last few years. 

 

When they did the first flush a few years ago I queried the instructions on the bottle of flushing fluid. The instructions stated that the fluid could remain in the system for up to 7 days. I asked why they only added the fluid on the day they were doing the flush. The reply... “Don't worry, it’ll be fine”. 

 

To my mind, the longer the flushing fluid is in the system the more it’ll loosen up the clag. Am I right, or doesn’t it make much difference?

 

Thanks,

Tony

 

[Ex Brummie]

Power Flushing solutions are more aggressive than other cleaning fluids you leave in and let circulate. A powerflush will take up to a day to be done properly, and use of the rad valves should flush one at a time. It is a job that can be shortcut, and often is. 10mm is restrictive, and depending on the circuit layout, you can be looking at insufficient flow to some radiators.

Balancing is imperative on any system, but more so on 10mm. Ask your engineer if he is flushing rads one at a time, and if he is rebalancing after the job is done. Also ask what inhibitor he is using. Querying the job can make him be a little more thorough. If you get the chance, have a look at what comes out. If it's not dirty, ask him why.

 If you're not happy, take it up with British Gas. If you are (and have been) paying for it, I would expect one flush to last more than a few years, but often an engineer will offer a powerflush as a fallback to an insoluble problem. If the system looks clean from the first run, I would take this up with BG  after the fitter has left. If it is dirty, ask the fitter why it should get so dirty after such a short time.

[OldGoat]

I have a similar 'challenge' with my home system - except that it's 15 and 22mm piping. I discussed it with a 'friendly plumber' and the consensus was that  the power flush was of 'marginal utility' with or without the fluid - but it was 'a nice little earner'.

The only real solution was to undo each joint and to clean it by hand. That's not a terribly practicable solution.

A 'possible' is drain the system down, give it a large dose, run for several days and repeat. Judicious use of a Birmingham Screwdriver (gently)  around the radiator connexions  should help (undoing the connections might be more profitable to you but not the technicians) 

[WotEver]

Thanks guys. We’re not paying for the flushes as they’re covered by our maintenance insurance agreement with BG. 

 

The last two flushes had large amounts of crud gather around the filters, so they’re cleaning out some of the muck but neither of them did one radiator at a time. The engineer who booked this flush made a point of stating that they must do every rad individually. 

 

When we bought the house new 25 years ago all of the rads used to get red hot, and they had never been balanced. A couple of rads haven’t been hot for a few years now and since the last engineer closed some down and then opened them back up several more stopped working, so it appears the crud is moving around a manifold somewhere. 

 

I’ll ask a few questions as you advise, to keep him on his toes, and also query why it’s got so mucky so quickly. I suspect the answer to the last question is that it wasn’t properly flushed the first two times. 

 

Thanks again for the input. 

 

Tony

 

Oh... probably unrelated but after the last engineer left we had an almighty banging coming from the boiler. I guessed it was kettling and reduced the boiler temp control, but since then our hot water has been scalding. So maybe the tank stat has also failed?

[OldGoat]

Quote

 

Did any of the 'technicians' dose the system with an inhibitor when the system was refilled after all the flushes??

[Tacet]

If you're not paying, you're fortunate.

 

I've just finished a long row with BG who had a service contract for a boiler - but it did not include power flushing.  BG insisted that the system needed flushing at a cost of £750.  But when that failed to fix the  boiler, it didn't stop the next technician (presumably unaware of the history) saying the system needed power flushing......More than once

 

Eventually (and it was a very long eventually) I got cross and created a fuss,  After a few more visits and a change of wiring harness(!) the boiler works again.  My feeling was that insisting on power flushing is a favourite ploy because it allows the technician to escape and if it is at the owner's expense, drums-up good business. 

 

In the middle of the long wait (over six months in total), having had no response from BG formal complaints procedure and a non-functioning boiler, I made a claim in the on-line Court for the the non-repair and wasted expense which led to the return of the £750.  I would much prefer BG to have simply fixed the boiler in a reasonable timescale.

 

 

[ditchcrawler]

My mum had an annual contract with BG to service her boiler for which she paid monthly, but it seems as though BG have a 13 month year effectively increasing the cost of this service by 8%. We got an independent chap, who also turned out to be a waterway enthousiast to do it and never looked back.

 

Edited January 3, 2019 by ditchcrawler
Spilling

[WotEver]

46 minutes ago, OldGoat said:

Did any of the 'technicians' dose the system with an inhibitor when the system was refilled after all the flushes??

Yup. 

[Boater Sam]

After years in the trade I can confirm that power flushing is a good earner for those that do it and a palliative for circulation problems.

Microbore systems using 10, 8 and  6 mm pipe work well if properly designed and balanced. Installed thousands without problem.

Flushing without removing valves and lock shields (especially thermostatic valves) is a waste of time if the system has lots of crud in it.

Fast flushing will just move it around to block up the next narrow point, be it a valve or a kink or a manifold.

The 7 day soak with descaling fluid will dissolve more iron oxides and lime scale and do a proper job.

If you are continually producing black sludge in a system I would be concerned that it is continually taking in fresh top up water or air and dissolving your radiators.

[nicknorman]

Yes I was going to ask if it’s a sealed system or fed from a small header tank with ball valve. If the latter it is easy for it to develop a thirst for new water without the leakage being particularly noticeable. A steady supply of fresh water brings in a steady supply of oxygen and limescale. Which is bad.

 

My mum had a “problem” radiator that wouldn’t get hot. 15mm pipe but a tortuous route. Various visits from BG contract people failed to fix. In the end I went down and simply disconnected  the radiator and extracted lots of black gloop from the pipe and the radiator. That was about 5 years ago and she routinely comments that it never worked so well in the 15 years prior to that. She cancelled the BG service contract as it was a waste of time and money.

Edited January 4, 2019 by nicknorman

[Boater Sam]

It is noticeable that a sealed system suffers much less from sludging/corrosion than a vented system. its the oxygen in the make up water that is the problem. Plus, if there is a leak the sealed system stops working, but there are folk who continually repressurise without finding out why it is necessary....................

[nicknorman]

5 minutes ago, Boater Sam said:

It is noticeable that a sealed system suffers much less from sludging/corrosion than a vented system. its the oxygen in the make up water that is the problem. Plus, if there is a leak the sealed system stops working, but there are folk who continually repressurise without finding out why it is necessary....................

Yes definitely. However it can be quite hard to find small leaks on a pressurised system as I know from personal experience. Our own system is pressurised and basically a sieve! Small leaks from TRVs evaporate with the heat. Leaks from air bleed bottles evaporate with the heat. Leaks from the crappy Volkera boiler’s own shutoff valves mostly evaporate with the heat. Leaks from the PRV disappear into a drain. Allin all it’s taken me years to trace and eliminate leaks and even now, I have to top up every year or so. Fortunately we live in a soft water area so limescale isn’t a problem.

 

One day soon I shall get around to installing a new system since the present one was old and knackered when moved into the house 15 years ago!

[Boater Sam]

38 minutes ago, nicknorman said:

Yes definitely. However it can be quite hard to find small leaks on a pressurised system as I know from personal experience. Our own system is pressurised and basically a sieve! Small leaks from TRVs evaporate with the heat. Leaks from air bleed bottles evaporate with the heat. Leaks from the crappy Volkera boiler’s own shutoff valves mostly evaporate with the heat. Leaks from the PRV disappear into a drain. Allin all it’s taken me years to trace and eliminate leaks and even now, I have to top up every year or so. Fortunately we live in a soft water area so limescale isn’t a problem.

 

One day soon I shall get around to installing a new system since the present one was old and knackered when moved into the house 15 years ago!

I sympathise, we had many such systems to do remedial work on, chasing the leaks could be frustrating. We used to cap of PRVs  and pressurise to 6 bar, found lots of leaks! Often in paper thin radiators. Rads are tested to 100psi (6.7 bar) new, boilers to 8 bar I think. Valves should stand 10 bar if the quality is there.

It boils (pun) down to using good valves, decent boilers, good autovent (or none) and a high standard of installation.

The biggest sealed system we ever installed was 48 radiators, 160,000 Btus. That's a lot of joints and valves!

I am shocked at the number of domestic systems I see where the filling loop is permanently installed "to top it up", in contravention of water bylaws of course.

[David Mack]

19 minutes ago, Boater Sam said:

 

I am shocked at the number of domestic systems I see where the filling loop is permanently installed "to top it up", in contravention of water bylaws of course.

But what incentive is there for the householder to disconnect the filling loop each time after use?

[Boater Sam]

None at all, that's why belt and braces there is a  non return valve on the heating pipe it connects to.

[WotEver]

5 hours ago, nicknorman said:

Yes I was going to ask if it’s a sealed system or fed from a small header tank with ball valve.

The latter. 

 

You've just reminded me that the ‘engineer’ who last visited and booked the flush also listed a replacement air admittance valve (I think that’s what he called it). 

[WotEver]

5 hours ago, Boater Sam said:

If you are continually producing black sludge in a system I would be concerned that it is continually taking in fresh top up water or air and dissolving your radiators.

Yep, understood. However, it’s never worked 100% even since the first flush so I’m wondering if the problem is simply 25 years of operation without a decent clean-out. 

 

No signs of any leaks anywhere - no orange or black staining on any joints with the exception of one radiator that had minimal rusting adjacent to a lockshield valve. BG replaced that rad a couple of years ago. 

[Sea Dog]

27 minutes ago, WotEver said:

However, it’s never worked 100% even since the first flush so I’m wondering if the problem is simply 25 years of operation without a decent clean-out. 

 

I'm pretty sure you'll be aware that inhibitor loses its effectiveness with time and that preserving the internals is more to do with regular preventative treatment than occasional clean out.  I think you mentioned that they are adding inhibitor after each flush so perhaps it's more to do with not enough inhibitor previously thus allowing the internals to corrode followed by ineffective corrective flushing now?  Let's hope they get on top of it this time.

[WotEver]

38 minutes ago, Sea Dog said:

I'm pretty sure you'll be aware that inhibitor loses its effectiveness with time and that preserving the internals is more to do with regular preventative treatment than occasional clean out.  I think you mentioned that they are adding inhibitor after each flush so perhaps it's more to do with not enough inhibitor previously thus allowing the internals to corrode followed by ineffective corrective flushing now?  Let's hope they get on top of it this time.

Following the advice I’ve received here, particularly Sam’s input, I’ve now escalated this to ‘a complaint’. They agree with Sam that a descaler should be put in the system 7 days prior to the flush so they’re going to investigate why it’s not been booked. They’ll also investigate why we now require a third flush - basically, why didn’t the first or second ones work? Why hasn’t it been pressure tested? Why didn’t they flush the system rad by rad? Etc. 

 

Then I think I’ll fit an in-line filter to keep the crud at bay. 

[nicknorman]

53 minutes ago, WotEver said:

Following the advice I’ve received here, particularly Sam’s input, I’ve now escalated this to ‘a complaint’. They agree with Sam that a descaler should be put in the system 7 days prior to the flush so they’re going to investigate why it’s not been booked. They’ll also investigate why we now require a third flush - basically, why didn’t the first or second ones work? Why hasn’t it been pressure tested? Why didn’t they flush the system rad by rad? Etc. 

 

Then I think I’ll fit an in-line filter to keep the crud at bay. 

At some point I’m going to replace our boiler (probably 25 years old) with a fancy new one. Trouble is modern boiler heat exchangers are more touchy about contamination etc. So my plan is to fit one of those filter thingies, run the system with the flushing agent for a week or so, drain, rinse and repeat s few times, prior to installing the new boiler. Needless to say I bought the filter some time ago but forgot to buy the round tuit required to fit it!

[nicknorman]

2 hours ago, WotEver said:

The latter. 

 

You've just reminded me that the ‘engineer’ who last visited and booked the flush also listed a replacement air admittance valve (I think that’s what he called it). 

An air admittance valve is the thing you put on a soil pipe vent inside a building so it can suck air in but not let nasty fumes out. The thing on a boiler is to let air out, whilst keeping the water in and is a bit like a carburettor flood valve - when the float drops the valve is opened to let air out, and when water comes rushing in to replace the air, the float is pushed up and seals the valve (or should do). I think they are just called “automatic air vent” or the like.

[jddevel]

7 hours ago, nicknorman said:

She cancelled the BG service contract as it was a waste of time and money.

Sound advice. Get an independent engineer who relies on repeat and word of mouth business. Having been in the new build house business and can compare the ridiculous installation prices quoted by BG with a good efficient self-employed registered engineer I know where I`d advise you spend your money. Now they use their branding to try and get you to deal with them on things outside gas services. What`s that all about!!! Reminds me of MPs. Experts at everything -except common sense.

[cuthound]

2 hours ago, WotEver said:

Following the advice I’ve received here, particularly Sam’s input, I’ve now escalated this to ‘a complaint’. They agree with Sam that a descaler should be put in the system 7 days prior to the flush so they’re going to investigate why it’s not been booked. They’ll also investigate why we now require a third flush - basically, why didn’t the first or second ones work? Why hasn’t it been pressure tested? Why didn’t they flush the system rad by rad? Etc. 

 

Then I think I’ll fit an in-line filter to keep the crud at bay. 

 

Personally would ditch BG, they are useless. I ditched them many years ago, when their "engineer" disagreed about my control valve leaking, despite me showing him the bubbles coming through a washing up liquid! Then they tried to charge me when I had a mantenance contract. I left telling them if they couldn't get the billing right, then how could they be trusted with something dangerous like gas ?

 

As jddevel says, find a trustworthy local guy, worth their weight in gold.

I would fit a Magnaclean filter. 

 

https://www.screwfix.com/p/adey-cp1-03-00022-01-2-magnetic-filtration-22mm/49961?tc=WT7&ds_kid=92700038507523690&gclsrc=aw.ds&ds_rl=1241687&ds_rl=1245250&ds_rl=1249404&gclid=Cj0KCQiApbzhBRDKARIsAIvZue_O6SKJkBAt5db8pjuO1kCabiJr0hMXAex89U6ZiCivJkUgasZYb_oaArNtEALw_wcB

 

Easy to install and acts as a dosing point for the future. I fitted on when the new boiler was fitted, and cleaned it every 3 months until the central heating system was clean. Now I clean it annually.

Edited January 4, 2019 by cuthound

[WotEver]

1 hour ago, nicknorman said:

I think they are just called “automatic air vent” or the like.

Yeah... that’s probably what he said

 

34 minutes ago, cuthound said:

I would fit a Magnaclean filter. 

Yep, that’s the one. Like Nick I've had one on my round tuit list for ages, although Nick’s ahead of me in actually buying one!