Expansion tank overflowing

tsue921i8wljb3

The feed and expansion tank in my parents house has started to overflow when the central heating is turned on.

The background to the problem is:

About four weeks ago when the cold weather started, my father noticed a problem with the boiler. It would start but then cut out. He called his boiler service man that he has always used. The man came and fitted a Riello burner to the old boiler saying that there was no need to completely replace the ~35 year old boiler.

My parents have remarked that the radiators are noticeably hotter now and that they are much quicker to heat up.

I have gone into the attic and observed that the f&e tank is full and water is escaping down the overflow pipe. The level does not seem to drop even overnight while the heating is not on.

While the system is cold I have emptied the f&e tank to just below the point where the ballcock valve kicks in. The ballcock valve brings the level of water up to about 6 inches and then cuts off as expected.

I have then turned the heating on and noticed the water level begin to rise in the f&e tank after about 30 minutes. The water does not come from the bent vent pipe above the f&e tank.

Reading other posts on the net about this issue a common fault seems to be a split coil in the cylinder. What is leading me to doubt this is the fact that the f&e tank is on a higher level than the cwst. Is it possible that it still could be a split coil?

I would really appreciate any advice on what I could do to identify and fix the problem. Thanks.

jimjimt

If your f+e is higher than your water tank and you had a split coil the heating water would leak into the domestic water so very highly unlikely.

If the problem was not their before the new burner was installed.
The first place I would look at is the boiler thermostat.
Is the new burner switching on and off periodically or always running as the new burner would have to be wired into the boiler thermostat ?

What temperature is the boiler stat set at ?

What type of new burner was installed ? Riello 40 perhaps ?

Installing a new burner on a 35 year boiler is a shame.
The old boiler would be lucky to get 65%-70% efficiency no matter how good a condition it is in. If you have to get a new boiler you will not be able to use the new burner.

If in doubt about anything forward pictures if you can.

tsue921i8wljb3

Thanks for the quick reply. Unfortunately I'm not at the house today. I'll be there tomorrow so will get the information then.

tsue921i8wljb3

The new burner is switching on and off periodically.

The boiler is a Sime Rio Type 1N3. It has a temp gauge and a temp dial on it. The temp gauge no longer works. The dial has no obvious mark to say what temp the boiler is set to. Somebody has scraped two lines in the metal as a guide I assume. At the minute going by this the boiler is set to 70°.

My father says he has been reducing the temp since the new burner was installed as the radiators were too hot in his opinion.

As far as I remember with the old burner the temp dial on the boiler was always set to it's maximum.

The new burner is a Riello 40 G3B.

So in your opinion I should keep reducing the temp setting on the boiler until the f&e tank stops overflowing?

jimjimt

It does seem to be pointing to an overheat problem. Your thermostat does need to be checked out and may be replaced or have the wiring check has the new burner may have been wired in to it.

Turn it down to a lower setting and try.

The nozzle in the new burner maybe over sized.

I think you need to talk to the plumber installer of the new burner and let him know you situation.

shane0007

If the burner has been replaced it should have been set up properly and the nozzle sized to suit the installation. Check with the installer and ask if it is flue gas analyised as this will give an indication of the ability of the installer.
Also of there is an issue with the thermostat, most OFTEC technicians should have a Fire Valve/Boiler Stat tester. This can test the temperature the stat is cutting in and out at. Failing that, replace the boiler stat.

tsue921i8wljb3

Thanks Jim and Shane. I will tell my father to contact the installer.

John T Carroll

Joel Future Stakeout wrote: »

The feed and expansion tank in my parents house has started to overflow when the central heating is turned on.

The background to the problem is:

About four weeks ago when the cold weather started, my father noticed a problem with the boiler. It would start but then cut out. He called his boiler service man that he has always used. The man came and fitted a Riello burner to the old boiler saying that there was no need to completely replace the ~35 year old boiler.

My parents have remarked that the radiators are noticeably hotter now and that they are much quicker to heat up.

I have gone into the attic and observed that the f&e tank is full and water is escaping down the overflow pipe. The level does not seem to drop even overnight while the heating is not on.

While the system is cold I have emptied the f&e tank to just below the point where the ballcock valve kicks in. The ballcock valve brings the level of water up to about 6 inches and then cuts off as expected.

I have then turned the heating on and noticed the water level begin to rise in the f&e tank after about 30 minutes. The water does not come from the bent vent pipe above the f&e tank.

Reading other posts on the net about this issue a common fault seems to be a split coil in the cylinder. What is leading me to doubt this is the fact that the f&e tank is on a higher level than the cwst. Is it possible that it still could be a split coil?

I would really appreciate any advice on what I could do to identify and fix the problem. Thanks.

Have a good look at the attachment...I know you didnt have pitching problems before but as other post(s) have suggested, the burner firing rate/ water temperature have changed since the fitting of the new burner. The system may have been on "borderline" pitching before the change. At the very least you can figure out what the Feed&Expansion Tank and Cold Feed configuration is.
You could also turn the thermost setting to minimum and see what happens, obviously if the water is being heated to > 100C, it will vent into the F&E Tank, thats what the vent is designed for, however, this is unlikely IF the Boiler is fitted with a separate overtemperature stat. If this operated, then it has to be manually reset. Forgot to mention...the circ pump speed, its just possible that the pump speed setting was increased from say 2 to 3. you could check this also and if at setting 3, reduce it to 2. I also have a very old system where the pump is pumping into the Boiler and the cold feed makeup is fed straight into the vent pipe which passes up adjacent to the F&E Tank, my pump speed is at "2".

shawneebuy

My expansion overflow pipe is running water in this hot weather, yet my expansion tank does not appear full.
Any ideas, please

shane0007

shawneebuy wrote: »

My expansion overflow pipe is running water in this hot weather, yet my expansion tank does not appear full.
Any ideas, please

It is obviously reaching the overflow pipe outlet to be overflowing.
Do you have solar panels installed?

shawneebuy

No solar panels,but attic is very hot up there. Syops when I run water into bathtub

shane0007

Probably just the level ball valve set too high & heat has expanded the level of the water a bit.
It would need resetting.

nanny9112013

please help i have the same problem. the overflow pipes outside never stop running water out of them and the only way to stop it is to run cold water in the bathroom sink can anyone help also my husband says the overflow pipe in the expansion tank is too low would this have anything to do with it.

scudo2

nanny9112013 wrote: »

please help i have the same problem. the overflow pipes outside never stop running water out of them and the only way to stop it is to run cold water in the bathroom sink can anyone help also my husband says the overflow pipe in the expansion tank is too low would this have anything to do with it.

Its no big deal, all you need is a plumber to replace the ball cock ( the valve that's filling the tank, normal wear and tear) and also to check the system.
Let us know where you live and if one of the service eng/plumbers live local they will respond, if nobody local on BOARDS.IE look up
Golden pages or ask a friend.
ps. Over flow pipe is ok. Its only doing what it was put there for. Overflow