money saving DIY system flush?

[NOTDIYFROMHELL]

People,

Could this be a potential money saving idea for DIYers. I can't see anything wrong with it and so invite the experts like Chrishutt, ChrisR, Oilman, Agile, gasman, PDM and anyone who knows their stuff to comment. Please keep the comments pleasant.

I recently, had to partially drain the system so decided to drain the system down completely and fit a drain cock on the return flow just before the boiler so that I can flush the system. There is a drain valve for the return pipe within the boiler, but the hole wasn't big enough, thus the need for this extra drains cock. A garden hosepipe was fitted to the drain cock to redirect the dirty water to a drain while allowing fresh water to enter the system via the filling loop. The water flow rate, thus pressure, is controlled by turning the handle on the filling loop. Clean water is allowed to flow through 1 or 2 radiator (depending on size) at a time until the water coming out of the hosepipe is clear. The central heating system was treated with some sludge remover (no brand name mentioned here as I don't advocate advertising) prior to the system flush.

Arguably, this kind of flushing can't replace a power flush, but for most cases I would say it's good enough and the money saving is quite huge. A power flush costs between GBP400-GBP600. It took me 20mins to fit the drain cock and the rest of time waiting for the water to clear.


Comments welcome.

 

[brentwood]

Well done- you've invented the wheel. Except now we use transporters. Beam me up Scotty!

 

[ChrisR]

Sure, that sort of thing will shift some muck from your system. BS xxxx says to use "full flow" connections to heating systems in order to flush them. Not that I've ever seen anyone fit them. Filling loops are quite restrictive so you get good pressure, for clearing a blockage, but not particularly good flow.

Fernox only claim that you can get "up to 80%" of the grot out of a system with powerflushing. Most users are delighted if long-since cold rads just get hot again, a slight cool bit wouldn't be noticed. So any flow can be a huge improvement.

Bad sludge is like cream consistency, it makes sense to me to use the mains to get rid of as much as rids quickly before being subtle with the rest, though there is a water-wastage issue here I've heard mentioned a couple of times.

One practice I copied is to put a 22mm T, upfacing elbow and compression cap, on the flow of a sealed system. It's for pouring inhibitors etc in once the water level is low enough, and also of course it provides a flush point.

Some powerflushing machines quote a flow rate. They're all pretty poor. 20 litres a minute is about all you're likely to get, that's a bucket in 30 seconds. Soft stuff is got into solution by flow reversals it's true, but to help shift serious grot , you can try serious flow. Remember the bucket.

What you can do, which isn't in the book, is adopt the U.S. loo flushing philosophy. It means having a couple of appropriate valves in your system; a full flow, 1/4 turn 22mm on that fill point I mentioned on the flow just after the boiler, is handy. Say you want to flush your boiler.

Take up smoking.

Close the valve on that fill point - which is going to become a dump point. Close all the radiator flow end valves. Open the return valves wide. Open the filling loop - assuming it's on the return pipe. Lots of air ( you need plenty of air) and water compresses in the radiators, and they all charge up - watch the pressure gauge, chicken out at 2.5 bar. Close the auto air release in the boiler, just because you can.

Tell someone else you want them to open the dump valve quickly - tell them to keep the rubbish which comes out, in the bucket, to show the punter, while you sidle off to have a fag.

Success is measurable in decibels, and how far the bucket flies.

 

[brentwood]

This will make an interesting experiment. I've just fitted a new combi onto an old system. It won't be powerflushed until tomorrow when its commissioned. However, I flushed it through as usual using the fill loop an the drain offs (one each on flow an return) and using the flow and return valves on the boiler to get it flowing in opposite directions (but not through the nice new heat exchanger). The filth was coming out in lumps even with most of the old pipe work being gone! Admittedly that was just plain water but tomorrow I'll see how much more I can get out with my shiny new Norstrom (hire shop one was out for a week)- better be a grands worth of muck!

 

[ChrisR]

I'd leave the iso vlaves shut when doing the PF too.

Probably Ferroquest is the best mittel to use on a same-day PF, try your local Plumbcenter. You could use Fernox DS40 which is more acidic and not so tecky.

 

[brentwood]

Iso valves will indeed be shut. Always put t's in flow and ret close to boiler for pflush. Usually use Ferroquest but was going to try Norstrom's own which came with it.

 

[ChrisR]

That'll possibly be a copy of some Fernox product. Norstrom were developing the flusher with Fernox. Then Fernox got wind of Norstom copying their brews and selling their own. Partnership no longer! Allegedly.

 

[NOTDIYFROMHELL]

"Well done- you've invented the wheel. Except now we use transporters. Beam me up Scotty!"

Hey Brentwood, the transporter can cost you and arm and a leg

Joking apart, please don't misunderstand my posting. I am a novice in this area and will not claim to have invented any wheel, be it square or circular. I just want to make sure what I've done is sensible so that people can either make good use of the method or don't jump into the same black hole.

 

[chrishutt]

Arguably, this kind of flushing can't replace a power flush, but for most cases I would say it's good enough and the money saving is quite huge

I have to disagree. I think it can and does replace power flushing! I've been using this method (with some refinements) for years and the results are entirely satisfactory. Why bother with an expensive and bulky power flushing machine?

Refinements - firstly I always fit a drain/filling point on both flow and return, using 15mm isolation (ball) valves which allow for a water tight and secure fixing to a hose (traditional drain off valves are a waste of space IMHO). Flushing can then be carried out in both directions by switching hose connections (or via a home-made manifold with valves).

Secondly, always do the flushing with the radiators full of air. Then the water flow is forced along the lower channel of the rad where the sludge is. Plus you can do tricks with pressurised air like ChrisR describes.

 

[oilman]

While the mains flush method will remove the sludge, I don't understand how you can get the magnatite off the radiator walls so the inhibitor will do an effective job. Not that it matters in many cases, some system cleaner, 2 weeks rumnning and then drain and refill every say five years will keep things in good condition.

 

[chrishutt]

I don't understand how you can get the magnetite off the radiator walls

Firstly, I've had poor results using chemical cleansers and even DS 40 trying to get hardened deposits off pipe walls, so I doubt if any system of flushing will reliably get things that clean. And does it really matter anyway?

Secondly, there's nothing to stop a chemical cleanser being circulated for a week or more (according to manufacturer's spec.) prior to flushing, or in between two flushing sessions. However in my experience such chemical cleansing will not remove much more than can be achieved with mains flushing alone.

 

[meldrew's_mate]

Have tried the constant flushing method and it does shift the big stuff succesfully. The reason I do it is to complete the PF using less chemical, though it is also used to clear the chemical at the end of the PF.

I've just bought a Magnaclean pro attachment for my flusher, haven't used it yet, though it looks like it will work well once the sludge is in solution.

I'll also try the vibraclean radiator basher when I get a chance, though it'll have to be much better than the rubber hammer method to justify dragging an SDS drill around the house.

Of much greater value appears to be the normal Magnaclean for post PF cleaning, but at £90 a time it could tip the customer over the edge. Much better would be a magnetic cleaner which could be easily removed after a few weeks to be used on another job.

The Fernox equivalent looks more versatile as it fits between std 1.5" pump valves so can be used on 28mm primaries (the Magnaclean comes with fitted valves but only at 22mm.

The big challenge for the chemical cleaner manufacturers is to make one which won't damage the alloys used in some HE boilers, but be strong enough to break down the sludge/scale/goo.

 

[oilman]

The Magnaclean Pro gets magnetite out of water that looks as though it hasn't got any in. It's may or may not remove a lot of sludge, but customers believe you have cleaned their system when you show them the build up on the magnets.

 

[ChrisR]

And does it really matter anyway?

Well yes it does, but not so much in the rads.
In rads it makes them less good as heat emitters and in h/e's it makes you pay more. But I don't expect any system to remain perfect, that's life. Where it does matter though is in primary sides of 2ndry h/e's - as a result they just don't shift the heat from the boiler so the boilers can fail to control the temp properly. At least many do. I note than many a condenser has a huge 2ndry h/e, perhaps that's part of the reason.
Must say if I were replacing a h/e on say a 24cdi I'd stick a 28cdi one on. Unless someone can give me a reason why not.

You can clean a 2ndry h/e to some extent with just water, but not very well, you do need chemicals. We don't see it but that must apply to primary h/e's too. I know it's taking the argument a bit far, but you wouldn't descale a kettle with a garden hose, would you!

OK DS40 won't remove absolutely everything, someone said - so what, it's a damn sight better than water.

 

[chrishutt]

Where it does matter though is in primary sides of 2ndry h/e's

Agreed, but as you've probably noted elsewhere, this is the one part of a combi boiler that is not normally treated in power flushing, since the diverter valve will not allow circulation through the secondary h/e from the CH pipes.

You have identified (elsewhere?) a rather clever way of cleaning both sides of the secondary h/e, but it does require two power flushers! perhaps you could patent a single power flush unit that simultaneously does both sides?

I note than many a condenser has a huge 2ndry h/e

Presumably to get the primary return temperature as low as possible to promote condensing.