heating gunk

tony melia

can anyone tell me is it possible to flush a heating system i have been told there is so called gunk in my system i think it,s called oxidisation pipes are less than half inch in size Boiler working and pump also but system not heating Can this problem be solved or will i have replace whole system grateful any help please
TM

ART6

Replace the system???:eek: It would need to be in some state to need to do that!

Deal with the first things first: All systems have some "gunk" in them. When it's first filled the radiators suffer from some internal oxidation due to the oxygen in the water, but as the oxygen is depleted it stops. Depending on whether you have a pressurised system or an atmospheric system, there are ways of flushing it, and a flushing liquid bought from a hardware store will make it easier. Somewhere in the system, probably near the boiler, there will be a drain valve -- a small brass valve with a hose connection and a square top on its spindle. Open that and the system will drain. If it's a pressuried system you'll need to make sure you keep it topped up through the filling valve. If it's atmospheric (a small header tank in the attic) it will fill itself. The trouble is that flushing introduces oxygenated water and starts the oxidation process all over again. Don't do it other than a last resort.

Before you do any of that though, check the balance of the system by making sure that the balance valve in the hot press tank (a red handled valve on a pipe near the bottom of the cylinder) is closed in to about 1/2 a turn. You might be simply putting all of the hot water from the boiler through the heating coil in the cylinder, thus bypassing the radiators.

If it's a pressurised system (a pressure gauge on the boiler and a red painted cylinder near it) then check the system pressure ( 1 to 1.5 bar) and the air valve on that cylinder (there have been several posts on that lately) to make sure that the diaphragm in the cylinder is not faulty.

Then the pump. Are you sure it's running? The fact that you might be able to hear it buzzing quietly doesn't mean it's pumping anything. If the boiler seems to be cutting out on temperature every minute or so, then the pump isn't doing what it should. Look at the setting screw on its casing (marked usually 1,2,3) and turn it up to 3. If that doesn't work, try tapping it with a hammer!!

If you post more details -- whether your system is pressurised or atmospheric, what boiler you have, etc, you'll get a lot of expert advice on this forum (not me-- I long ago gave up claiming any expertise on anything:D)

slimjimmc

Art6, is it not fair to say there is always dissolved oxygen in the heating circuit, some of it is vented but not all, hence the need for a few litres of an inhibitor to prevent excessive gunk buildup? Particularily with open systems.

copper12

Art6 could not have said it better myself
Slimjimmc small detail don’t you think

slimjimmc

It may well be. it's just that plumbers I've met have recommended an inhibitor for the reason I mention. When Art6 stated that oxidation stops after a while it triggered my curiousity to know if the information I was given was of any practical benefit or just an unncecessary expense.

tony melia

thank you all for repling Just to add when system first failed to heat it was noticed the pump was making loud noise and was replaced.The system is an open system gas boiler is working then over heats and cuts out
as i said pipes are less than half inch and have been told system blocked with gunk and whole system will have to be replaced including boiler
apart from being drastic I would not able to afford to do this Maybe i am grabbing at straws but i am hoping for an alternative
TM:mad:

ShowAndGo

I am feeling your pain Tony, I am going through a similar problem at the moment!

If the problem is a blocked pipe, is it not possible to narrow down where it is, rather than replace the whole system? Test if heat is going to the cylinder on its own (ie just heat the water, no rads). If it is heating the water then test each zone.

ART6

tony melia wrote: »

thank you all for repling Just to add when system first failed to heat it was noticed the pump was making loud noise and was replaced.The system is an open system gas boiler is working then over heats and cuts out
as i said pipes are less than half inch and have been told system blocked with gunk and whole system will have to be replaced including boiler
apart from being drastic I would not able to afford to do this Maybe i am grabbing at straws but i am hoping for an alternative
TM:mad:

Atmospheric (open) systems are 15 mm outside diameter copper pipe (or 1/2 inch if you prefer). I have not personally ever come across a system that was so blocked with this "gunk" that everything including the boiler must be replaced. Since generally the "gunk" is a result of oxidation inside the radiators, I would expect all of them to be imitating sieves long before the system blocks. Even if there is a blockage somewhere, it's perfectly possible to selectively flush the system to clear it, although I have difficulty in believing that gunk is the problem.

So. The first rule of diagnostics is "what was the last thing done?" Pump changed? OK, is it installed properly (the right way round)? Is it wired correctly -- actually running? Is it connected to the thermostat on the pipework that's intended to switch it on and off? The fundamental issue as I see it is that the boiler is working fine but the water in it isn't going anywhere, hence the overheating and cutting out. If you do have an atmospheric system then either the pump isn't working or there's a valve closed somewhere -- the balance valve on the hot tank and all or most of the rads turned off.

The pump casing will have an arrow on it that shows the direction of flow, and it could be on the bottom pipe or the top to the boiler. If it's on the bottom pipe then the arrow should be pointing towards the boiler, and if it's on the top pipe it should be pointing away from it. So, for example, if it is the wrong way round in the top pipe it will be trying to oppose the thermal lift of the boiler, which is a no win situation for both of them.

Then the next obvious question. Is the header tank for the atmospheric system full? If it isn't you could have simply run out of water in the system. If the tank is empty make sure the ball valve has dropped to admit water -- they get so little use that they often stick closed.

311

I have this machine in my van for jobs like this ,it completely clears systems that were not working at all.

http://www.fernox.com/?cccpage=powerflow_flushing_pump&sub=7

tony melia

sorry i took so long replying have been given estimate of 2200 euro to replace all piping using existing boiler and rads My house 3 bed bungalow with 6 rads Is this a fair quote or am i been had

TM

ART6

tony melia wrote: »

sorry i took so long replying have been given estimate of 2200 euro to replace all piping using existing boiler and rads My house 3 bed bungalow with 6 rads Is this a fair quote or am i been had

TM

Or find someone like 311 and get him to flush your system, or even flush it yourself with a garden hose and some playing tunes on radiator valves to clear the system. Honestly, I have seen some systems with a fair bit of clag in them, but for one to be so filled with "gunk" that it becomes plugged and inoperable sounds incredible to me. The "gunk" in CH comes mainly from oxidation in the radiators, and that is self limiting unless you have a severe leak somewhere that needs continual topping up. If that were the case your radiators would be leaking like sieves by now. So, the answer to your question, in my book, is if your rads are OK then get the system flushed as a start, but I remain to be convinced that that is your problem.

311

The only pipework that would ever need replacing on a heating system ,is gun barrel pipe(normally when the system isn't working right).
It sounds like you have copper piping though ,which sounds strange that someone would change the pipe and not the radiators.

You never need to replace copper pipe because of sludge ,you need to clean everything though. Theres more dirt in the radiators and boiler ,than in a few pipes.

Get another quote and ask the guy what your options are.

EDIT : Just to be sure I'm not missing something here ,if you are living in a hard water area and the tank is fed from the mains. Then that is a completely different story. Scaling is a different problem than sludge ,it can be treated but it's far more difficult process and takes longer to break down.
I missed this because I mostly work in Dublin ,scaling can cause the boiler to overheat but it might be just around the boiler area(heat exchanger)

tony melia

thanks for all your replies I have another fella looking at it today Iwill let you know what happens
T M