Powerflush

[ghostlymoron]

This is another unashamed non boat question as I want to tap into the combined knowledge of the forum. The central heating system at Ghostly Towers is malfunctioning. Most of the radiators are cold or at best warm and not putting out any useful heat. I bled them all which made no difference so I called out the firm with whom we have a maintenance contract. Their plumber arrived, turned all the rads up full and checked the boiler where he found the heat exchanger corroded and leaking. This has now been replaced at no charge. However the rads arecstill not heating up and he recommmends a powerflush which will be chargeable.
Has anyone had this done and did it work?
Incidentally, the boiler is a Worcester Bosch condensing type fitted in 2005 and I understand that the heat exchangers last on average 10 years. (Our old boiler was still going strong at 30+) but much lower efficiency.

 

[Ferring]

Yes did have a powerflush about 3 years ago. Symptoms were boiler heating cycling due to high temperature in the boiler but not reaching the radiators. This was after a full service and pump replacement. Made a massive improvement and heating system now 100%. The powerflush was done by BG and cost about 750 pound with a long term guarantee of future free flushes if required.

 

[NormanB]

First off your system would benefit from cleaning. The problem is finding anyone who would do it properly. Many will turn up with a big pump, connect it and achieve not very much. A question must also be asked about the effectiveness of your system circulation pump. Is it rotating? ( you can buy a wee rotating magnet for testing in a plumbers store).

I am surprised that your heat exchanger has failed so soon and I am sure Worcester would not expect their boilers to fail in that timescale UNLESS the water chemistry was neglected. Your maintenance contract has not really delivered for you in that regard.

Of course it depends on how handy you are but it is not too difficult to achieve an improvement yourself.
This assumes you have a functioning pump ( replace if not proven).
1. Drain system fully.
2. Remove all radiators and flush using garden hose.
3. Replace radiators but isolate at both sides.
4. Fill system with a system cleaner and vent.
5. Circulate hot in accordance with instructions.
6. Dump the lot.
7. Dose with Fernox inhibitor, refill and open up radiators and vent.
8. Put system in use.

If you had an average side house you could do this in a full working day.

 

[ghostlymoron]

First off your system would benefit from cleaning. The problem is finding anyone who would do it properly. Many will turn up with a big pump, connect it and achieve not very much. A question must also be asked about the effectiveness of your system circulation pump. Is it rotating? ( you can buy a wee rotating magnet for testing in a plumbers store).

I am surprised that your heat exchanger has failed so soon and I am sure Worcester would not expect their boilers to fail in that timescale UNLESS the water chemistry was neglected. Your maintenance contract has not really delivered for you in that regard.

Of course it depends on how handy you are but it is not too difficult to achieve an improvement yourself.
This assumes you have a functioning pump ( replace if not proven).
1. Drain system fully.
2. Remove all radiators and flush using garden hose.
3. Replace radiators but isolate at both sides.
4. Fill system with a system cleaner and vent.
5. Circulate hot in accordance with instructions.
6. Dump the lot.
7. Dose with Fernox inhibitor, refill and open up radiators and vent.
8. Put system in use.

If you had an average side house you could do this in a full working day.

We have a large 3 storey house with 14 rads and 3 flights of stairs so I don't fancy lugging them all outside to flush them although I am a competent amateur plumber. I can see the logic behind your method though. Thanks for you advice.
The maintenance firm who also installed the boiler have quoted £650 for flushing but I'm not sure they guarantee it as BG apparently do.

 

[ghostlymoron]

Norman, I did remove and flush the bathroom radiator when I redid the bathroom a couple of year's ago. This rad is working fine. I've found that you can remove a radiator without draining the system. Close flow and return valves, loosen rad connections, swivel till rad below horizontal, fully unscrew connections, remove and keep connections at the top till you're outside.

 

[NormanS]

If your maintenance contract is with BG, and if their man has recommended a power flush, I think you will find that BG will no longer cover your system until and unless a power flush is carried out to their satisfaction. That was the position that I found myself in. I knew that mine didn't need a power flush, but realistically the boiler was coming to the end of its life, so I finished up having a new boiler installed.

No doubt, other maintenance companies may have different conditions, but worth checking on.

Before installing a new boiler, BG carry out a power flush, and the person doing it confirmed that it hadn't needed it. However, now that it's done, BG guarantee it for ever.

 

[lw395]

I suspect your maintenance contract people have not aintained the inhibitor in the system?
There are things you can try, such as descalers and cleaners which you add to the system.
E.g Sentinal x 800.
But a powerflush will often use fiercer chemicals such as phosphoric acid.
Do you have a magnetic filter protecting the boiler from crud from the rads?

Phone around for powerflushing, someone in the office was whinig about paying £300, which does not seem all that bad for a 6 hour job using a fair amount of chemistry.

 

[NormanB]

We have a large 3 storey house with 14 rads and 3 flights of stairs so I don't fancy lugging them all outside to flush them although I am a competent amateur plumber. I can see the logic behind your method though. Thanks for you advice.
The maintenance firm who also installed the boiler have quoted £650 for flushing but I'm not sure they guarantee it as BG apparently do.

OK 2 days then. lol.

Check your pumps is spinning before doing anything tho.

 

[Heckler]

We have a large 3 storey house with 14 rads and 3 flights of stairs so I don't fancy lugging them all outside to flush them although I am a competent amateur plumber. I can see the logic behind your method though. Thanks for you advice.
The maintenance firm who also installed the boiler have quoted £650 for flushing but I'm not sure they guarantee it as BG apparently do.

I have found that the room stats on the rads stick and stop the water circulating. All the symptoms of an air lock. Take the knob off, bit of WD40 or similar on the spindle and a pair of pliars to wriggle them in and out and away they go!
Stu

 

[VicS]

I have found that the room stats on the rads stick and stop the water circulating. All the symptoms of an air lock. Take the knob off, bit of WD40 or similar on the spindle and a pair of pliars to wriggle them in and out and away they go!
Stu

I reckon TRVs are one of the most unsatisfactory parts of the CH system.

I have couple that can be dealt with in the way you describe, although only one of them sticks.

Al the rest are old Drayton valves which require a somewhat different approach. but I try to avoid trouble with those by opening them fully when the heating is not in use during the summer.

 

[ghostlymoron]

I have found that the room stats on the rads stick and stop the water circulating. All the symptoms of an air lock. Take the knob off, bit of WD40 or similar on the spindle and a pair of pliars to wriggle them in and out and away they go!
Stu

I know that and have checked it. Good tip for others though.

 

[NormanB]

Yeah TRVs can stick and be relieved in the manner described. However, it would be very unusual for all TRVs on all of the radiators to fail closed at the same time.

 

[Norman_E]

This is another unashamed non boat question as I want to tap into the combined knowledge of the forum. The central heating system at Ghostly Towers is malfunctioning. Most of the radiators are cold or at best warm and not putting out any useful heat. I bled them all which made no difference so I called out the firm with whom we have a maintenance contract. Their plumber arrived, turned all the rads up full and checked the boiler where he found the heat exchanger corroded and leaking. This has now been replaced at no charge. However the rads arecstill not heating up and he recommmends a powerflush which will be chargeable.
Has anyone had this done and did it work?
Incidentally, the boiler is a Worcester Bosch condensing type fitted in 2005 and I understand that the heat exchangers last on average 10 years. (Our old boiler was still going strong at 30+) but much lower efficiency.

I deleted this because my text ended up tangled with the original post, so here it is again.

I refuse to replace my 30+ year old boiler even though its a big one and only about 70% efficient against the claimed 90+ percent efficiency of the short lived condensing boilers that were mandated to us by the towering intellect of John Prescott. The problem is that it is well known that modern condensing boilers have no where near the lifespan of old cast iron ones like mine. After seeing a quote for a new boiler I quickly worked out that even if gas prices doubled it would take about 12 years for the likely efficiency saving to repay the initial cost.

 

[ghostlymoron]

I deleted this because my text ended up tangled with the original post, so here it is again.

I refuse to replace my 30+ year old boiler even though its a big one and only about 70% efficient against the claimed 90+ percent efficiency of the short lived condensing boilers that were mandated to us by the towering intellect of John Prescott. The problem is that it is well known that modern condensing boilers have no where near the lifespan of old cast iron ones like mine. After seeing a quote for a new boiler I quickly worked out that even if gas prices doubled it would take about 12 years for the likely efficiency saving to repay the initial cost.

When we replaced our old boiler with a modern condensing Worcester Bosch we cut gas consumption by 30% which is about £300 pa. We could have a new boiler every 3 years for that. But we've had this one 11 years so I figure I'm ahead of the game.

 

[NickRobinson]

When we replaced our old boiler with a modern condensing Worcester Bosch we cut gas consumption by 30% which is about £300 pa. We could have a new boiler every 3 years for that. But we've had this one 11 years so I figure I'm ahead of the game.

£900 for a boiler for three story house? Bargain. However I only use c.£500pa on my indestructible non electronic cast iron Gloworm. My break even would be 2x longer than the design life even not factoring the frequent servicing they need.

The new ones are made out of tinfoil and XZ Spectrums, I was told...

(your fault if my boiler dies today.....)

 

[lw395]

Yeah TRVs can stick and be relieved in the manner described. However, it would be very unusual for all TRVs on all of the radiators to fail closed at the same time.

Unless there is a common cause such as a load of gunge?

 

[lw395]

£900 for a boiler for three story house? Bargain. However I only use c.£500pa on my indestructible non electronic cast iron Gloworm. My break even would be 2x longer than the design life even not factoring the frequent servicing they need.

The new ones are made out of tinfoil and XZ Spectrums, I was told...

(your fault if my boiler dies today.....)

Fitting an old skool cast iron boiler is not an option.
£900 for a boiler? I can buy one for £700, but labour to fit is going to be rather more than £200.
A powerflush is pretty much obligatory as the only way to meet part L of the bewildering regulations.
Also if you've ever become familiar with the inner workings of a modern combi boiler, you may find they are quite intolerant of dirt.
I've had apart a Worceser Combi, the diverter valve which selects rads or water heating relies on water going through little holes about 1.5 or 2mm. Just a few grammes of well placed dirt will leave the rads cold.

 

[ex-Gladys]

I had a 1972 Worcester boiler in current house, and knew it was on it's last legs. Moved in 7 years ago, and combined fuel bill was around £150 pcm for a 3 bed house. Boiler was replaced in 2010 along with the rads, and I now have a Vaillant combi in the loft with a Combimate for the feed to the boiler and a TF1 magnetic job as well. Heat exchanger is still as clean as the day it was installed. Fuel bills are now less than half what they were in 2010 (£73 pcm), or £5,500 to date or £9,240 if I need to replace at 10 years, and a replacement boiler at 10 years will only be about £1500.

That's roughly an extra £750 a year to spend on the boat! Bargain!

 

[wombat88]

BG did it for us. Brought about by 10 year old BG boiler clogging up.

Went on all day, huge amount of black and grey gunge produced, system was new in the 1970s and never touched since apart for valves etc. Also installed a magnet thingy.

Thoughts? Big difference. Expensive but worth it and now the whole thing is covered by guarantee (not sure tho about what happens when the radiators finally rust through).

 

[reeac]

BG did it for us. Brought about by 10 year old BG boiler clogging up.

Went on all day, huge amount of black and grey gunge produced, system was new in the 1970s and never touched since apart for valves etc. Also installed a magnet thingy.

Thoughts? Big difference. Expensive but worth it and now the whole thing is covered by guarantee (not sure tho about what happens when the radiators finally rust through).

I do wonder, when reading such stories, what kind of inhibitor (if any) was in the system. Our 19 year old system has, so far, shown no evidence of blocking up or sticking TRVs and very little need for radiator bleeding. It's efficiency was originally stated to be about 85 percent and it continues to show that when serviced so I'll keep it until it goes severely wrong.