POWERFLUSHING central heating system

harryhound

This time last year, I moved into a dorma bungalow (ie a bungalow with rooms in the roof). It was an executor's sale, so the seller did not live locally knew sweet FA about what he was selling.
It is one of an estate built 30 years ago, and the system looks like it was almost installed as an afterthought as it looks like the electrician got there first and in some places the single panel radiators almost block the power points and are inappropriate for the rooms involved.
It is the traditional design, with the expansion tank in the tiny loft (together with TWO hot water feed tanks because there is not room for one large one.)
The pipework is all in the upstairs floor and for the downstairs radiators drops down from the ceiling behind the curtains. This means that each radiator on the ground floor tends to have its own difficult to get at drain-off point. There are only to pipes out of the boiler and BOTH are fitted with drain points, above the boiler.
The balanced flue boiler has been replaced by the previous resident and is physically smaller than the original outline on the wall inside its kitchen cupboard; though it is not a condensing boiler.

That is the back ground this is my immediate "problem":

The large "L" shaped lounge/diner is inadequately heated, partly because its windows and patio door face North and East. The previous stay at home occupant reacted by building an ugly fake stone fireplace, complete with a gas balanced flue inset fire and a supply pipe running round the outside of the house from the gas boiler.

The fire seems pretty knackered and anyway I want to remove the fireplace.

The neighbours are not surprised that the radiators in the lounge/diner are inadequate, so where theirs.

I propose to replace the two radiators with larger output but double panel replacements; while having the room "skimmed" to get rid of the "artex" and repair the damage to the walls in several places.

Any advice :

If I were to fit a magnetic filter, where is the best place to put it?

I am willing to bet that I will get an airlock; if so any advice on bottom filling via the drain off points ?

There appears to be a nasty looking rust coloured sludge in the bottom of the expansion tank that I will siphon and then sponge-out to clean the tank ?

Should I drain off all the down-stairs radiators, or would just refilling with a cleaner be enough to clean out the other downstairs rads ?

How do I estimate the capacity of the system when buying the cleaner and then the long term protector to use in the system ? Is there a rule of thumb ?

Any one want a couple of 1980s fin-backed single panel radiators

harryhound

Any thoughts ?

I have found a manual for the Potterton Suprima boiler on the interweb (78% efficient with a cast iron heat exchanger (so hopefully no tiny micro tubes inside that (?!) I drained down the system via the radiator nearest the front door and then each of the two radiators for replacement via the drain plug for each of their part of the circuit.
Has a struggle with one of the two little plugs, it was of a domed rubber washer, rather than the flat rubber usual washer design and the little "jumper" on which this had been mounted pulled out of the screw plug and was left jammed in the hole (bit of a flood when long handled pliers dislodged that one).
Both rubbers are as hard and flexible as concrete, so will need to be cut off and replaced with a new flat washer slipped onto the central brass prong?

The fluid in the system has come out with minimal black gunge - so perhaps the guys who replaced the boiler did a good job. Perhaps they were responsible for the different type of rubber washer in one of the drain plugs.

Now for the replacement rads and new TRVs (Thermostatic Radiator Valve) to replace the 30 something year old originals!

harryhound

Oh dear this is turning into my private blog.

I have replaced both the radiators in the living room, but as the house thermostat has been put in the living room too I will need to fit the upstairs 3 bedrooms to avoid the current tenancy to overheat the upstairs with TRVs (thermostatic valves) too.

As the fluid that has come out of the rads is remarkably clean and the boiler has a cast iron heat exchanger, I think the guys who fitted the "new" boiler must have done a good job and I will just flush it with clean water then introduce the correct concentration of protection fluid, probably Fernox ?

southcoastrgi

if it's fairly clean then as you say give it a flush through with water

fernox or sentinal (although i normally use the latter x100) 1 bottle per 10 rads

magnetic filter is best on the return back to the boiler, although on the flow will work too, just make sure if it has an arrow on the body that this facing the correct way

the washers would have been flat when installed & have got doomed over time & by overtightening, there are two different types of drainoffcocks "A" & "B" they have diff size washers, pics below so you can get the right size replacements

this is A




this is B

harryhound

Many thanks for the reply.

I managed to find a plumbers merchant, where the counter was still manned by guys who knew the job. We sussed out that I had the smaller grottier drain cocks and I needed the small flat washers to fit. [The larger c0ck works like a tap and does not dribble out all over the place].

The job is not as simple as some of the U-tube clips suggest.

Here are my observations:

A. There could be perished rubber washer still stuck up the drain c0ck to clean out.

B. However many old towels and oven roasting dishes you have, you cannot have too many.

C. As the house heats up the next morning , beware of liquid still in the pipes doing the same, expanding and possibly causing a siphon effect. If you open a bleed valve and there is the sound of air being sucked in it must mean water is flowing out somewhere else - two person job to cover both floors unless you want to rush about in a panic.

D. Have a dry run to make sure you have tools, that will fit into small spaces and fit various sizes of nuts screws etc.; not to mention the hexagonal key needed for removing old type radiator fittings.

E. The radiators have a large threaded hole dating back to the days of the steam engine, as these days they are fed by 15mm pipes (or microbore but that is another story), so now the fitting that screws into the radiator has been redesigned to fit to a 15mm TRV and lock shield valve and so offers a smaller thread to the outside world.

F. What is more THEY HAVE A LONGER STEM (presumably to make sure there is adequate space for the chunkier TRV to be fitted next to the radiator). Depending on how your radiators are fitted and the amount of "slack" that can be dragged through the wall or down behind the curtains or out of the floorboards, you may need to lengthen the pipe to one end of the radiator to make a neat job of it. So how good are your soldering skills and slickness on wiping the capillary solder fitting?. It is not just a spanner job now!

G. As what I flushed out of the rads and the probably 7 year old Potterton boiler [78% efficient with a cast iron heat exchanger] was pretty well clean (well done the boiler replacement team) I just used ordinary water to flush through the system. And what a miracle I managed to so it without having to bottom fill [That is pushing water back up through the drain c0cks, from the mains via a length of hose pipe] .

H. When (re)using compression fittings, smearing the "olive" and the threads with jointing compound should mean no leaks [Boss White is the best know brand but others are available]

[I have since noticed that plumbers uprating old radiators to TRVs tend to wrap the threads of the compression fitting in white PTFE tape - why do they do this? I would have thought that if the water got past the olive it would weep out round the pipe not through the threads?]

I. To clean the grot, that had been left in the bottom of the the expansion tank, I plugged the pipe leading to the radiators with a handy "cork" and filled it up . Then I emptied it again using a length of hose pipe as a syphon, as I scrubbed at the gunge in the bottom of the tank. Obviously there was lots of water on hand from the ball c0ck that could be vacuumed up by the syphon effect.

After I had refitted/replaced the 4 radiators and flushed through the time came for the refilling to the brim and leaving the system over pressure overnight to see if anything started dripping.
[one radiator die drip but that turned out to be my folly: I had losened off one end of the radiator again because I was having a problem getting the valve at the other end to line up and thread properly - I forgot to re-tighten the first end].

J Adding the additive: I ran the system for a day, on just water, to check that all the radiators were heating up then tried the drain c0ck s again and was pleased to see the water was still clear; so I made up a funnel out of an old poly drinks bottle with a length of old micro-bore gas pipe. I did not want to risk loss of the Fernox (expensive) additive, had there been a serious leak problem. So I fed the home made funnel's length of micro-bore from the expansion tank into the radiator top-up expansion pipe. Opened a drain c0ck and sucked the contents of the funnel topped up from the Fernox container into the system, before allowing fresh water via the ball c0ck to top up the tank. ............

I will be fiddling about, come the winter, adjusting the thermostat on the TRVs and the lock shield valves, to get the right temperatures in the main rooms of the house.
.

JustSteph

Hi there, We recently had our first service for our Homecare agreement with British Gas and we were told we need a powerflush as the radiators furthest away from the boiler (combi) do not heat up properly. We were then quoted £619 for them to do it! Does it really need a powerflush or is it something we can get done cheaper or even better, do ourselves? Or is it worth getting BG to do it for their lifetime guarantee?

unclebulgaria

JustSteph wrote: »

Hi there, We recently had our first service for our Homecare agreement with British Gas and we were told we need a powerflush as the radiators furthest away from the boiler (combi) do not heat up properly. We were then quoted £619 for them to do it! Does it really need a powerflush or is it something we can get done cheaper or even better, do ourselves? Or is it worth getting BG to do it for their lifetime guarantee?

Don't just go for BG, their engineers get bonus's for work they pass on.
Try a local guy who has maybe done work for family or friends so you know he's not a twit at least.
Just because the furthest rad isn't getting warm doesn't mean its sludge, it may need the system balancing.
Get more advice.
Just in case you do need a powerflush, when they do it it will take all day to do and each rad should be flushed individually by isolating the remaining rads then each rad in turn. Have a look on the net there is lots of info on how its carried out.
If you have micro bore don't waste your money.

mwbrown

We had a service contract with BG (to repair our old Biasi boiler - which to their credit they kept it running for 5 years longer than I thought they would - it was a terrible boiler (age was about 15 years old so we were informed!)).

Usually the first thing BG advised when they came out to repair it was that it would be beneficial for it to be powerflushed (all the black gunk in the system) even in the really cold winter a couple of years ago (we had 3 different engineers out in a week as the boiler wouldn't run for very long and was told every time that it was blocked and needed powerflushing - eventually got an independent guy who came and had a quick look on the Saturday morning and he found the issue in about 3 mins flat (which the 3 BG engineers spent a good few hours between them trying to solve!!!!), turns out one of the pipes above the kitchen ceiling had frozen :rotfl:

Fast forward a couple of years and we finally bit the bullet and got the boiler replaced (system was flushed and various additives were added and new boiler fitted - which is working great and no issues)... The installer cleaned out the magnaclean filter a couple of times after running the sytem and loads of gunk game out.

I have cleaned the filter out a couple of times in the last few weeks and the first time a reasonable amount of gunk came out, but upon cleaning it today there was about 25% of the gunk in the filter this time compared to the first time. So don't believe all BG says about the system needing a powerflush (our main issue was the biasi boiler we had wouldnt heat all the rads up (total of 7 rads - 2 of which are quite big!) if we tried to use all 7 rads at once - new boiler was installed along with wireless roomstat and trvs to all the rads and the house is toasty warm constantly.

sorry for the long post

Mike

southcoastrgi

mwbrown wrote: »

Fast forward a couple of years and we finally bit the bullet and got the boiler replaced (system was flushed and various additives were added and new boiler fitted - which is working great and no issues)... The installer cleaned out the magnaclean filter a couple of times after running the sytem and loads of gunk game out.

I have cleaned the filter out a couple of times in the last few weeks and the first time a reasonable amount of gunk came out, but upon cleaning it today there was about 25% of the gunk in the filter this time compared to the first time. So don't believe all BG says about the system needing a powerflush (our main issue was the biasi boiler we had wouldnt heat all the rads up (total of 7 rads - 2 of which are quite big!) if we tried to use all 7 rads at once - new boiler was installed along with wireless roomstat and trvs to all the rads and the house is toasty warm constantly.

sorry for the long post

Mike

Which goes to prove 2 things

1st the guy that flushed it didn't do it properly, because if he had you wouldn't have to clean the magnaclean, centainly not as much as you say.

2nd it did need flushing so BG were correct

mwbrown

southcoastrgi wrote: »

Which goes to prove 2 things

1st the guy that flushed it didn't do it properly, because if he had you wouldn't have to clean the magnaclean, centainly not as much as you say.

We were informed by the installer that it was advisable for the filter to be cleaned out in the first couple of months to collect any debris that was floating round the system rather than waiting until the first service was due......

2nd it did need flushing so BG were correct

It obviously didn't need a powerflush as BG advised us on numerous occasions (the point being we had a frozen pipe above the ceiling (on three occasions in a bad winter!!!) and they were adamant that it needed a powerflush - which obviously it didn't need it....
the installer never did a powerflush on the system