Boiler constantly switching off and on

[buckers]

Hi,
This is my first post so please be gentle. Moved into my house 4 years ago and had boiler serviced/ fixed as had no heat. They replaced pump, flushed system and serviced the boiler. Its never actually been a working system in my eyes. Main issue is when on timed heat and water the boiler will fire correctly at the exact time but after say 20 mins will shut down. The home is still freezing. It will eventually fire back up could be in 5 mins or 45 mins later. I have to switch the power to the timer off and wait a few mins for it to re-fire. This can happen 7-8 times each day. Was also told as my boiler is old the timer needs both water and heating on to allow "heating only" to work. In the summer i can just use water but in the winter i need to use both or else the heting wont come on. I have half rectified the rads taking 2 hours to heat up downstairs by balancing the systen as per another thread so hope in a few days to equal the heating across the system. My details are below if anyone can help as this has been going on for ages.

Boiler Myson Orion Fanfare 60 si ( approx 20 years old)
Timer wired to boiler is Drayton Lifestyle LP241
Old Sunvic room stat in the ground hallway
Pump on cylinder is Grungfos UPS 15-50

P.s

A sparkie mate has checked the stat and said it is kicking in, but the cover was loose but 12 months ago and i put a meter across 2 live wires by mistake and got a little kick. Think this is when my on/off issue started. Have I blown something in the timer?

Many thanks for looking

Ian

 

[mountainman]

Hi Ian
Sounds like a circulation issue at first thought.
20 year old system could have several issues.

I think you could do with a visit from a heating engineer.

 

[buckers]

Hi Mountainman,

Thanks for the input, the heating does get nice a hot eventually and is actually allot better since Ive balanced the downstairs to approx 80% and upstairs 20% heat this morning. The main issue is the constant stopping and starting of the boiler...... grrrr

 

[doitmyself]

Main issue is when on timed heat and water the boiler will fire correctly at the exact time but after say 20 mins will shut down. The home is still freezing. It will eventually fire back up could be in 5 mins or 45 mins later. I have to switch the power to the timer off and wait a few mins for it to re-fire. This can happen 7-8 times each day.

What is the setting of the boiler thermostat?

Was also told as my boiler is old the timer needs both water and heating on to allow "heating only" to work. In the summer i can just use water but in the winter i need to use both or else the heating wont come on.

Sounds as if you have a pumped heating/gravity hot water system. If that is the case, you will have two 22mm pipes and two 28mm pipes coming out of the top of the boiler.

Does the pump run when heating is on (use a screwdriver as a stethoscope to check)

12 months ago and i put a meter across 2 live wires by mistake and got a little kick. Think this is when my on/off issue started. Have I blown something in the timer?

Presumably trying to check if it was working. What were you measuring - resistance?

 

[buckers]

What is the setting of the boiler thermostat?

Its on number 5 of 1-7. Was told that this didnt work and not to use it.


Sounds as if you have a pumped heating/gravity hot water system. If that is the case, you will have two 22mm pipes and two 28mm pipes coming out of the top of the boiler.

Does the pump run when heating is on (use a screwdriver as a stethoscope to check)
The pump runs fine had the inspection screw out and it works on all 3 speeds. Just checked the room stat now and had it set to 22. moved to round to 16 where it clicked and cut the boiler out so looks like that is working fine.

Presumably trying to check if it was working. What were you measuring - resistance?

Yeah was checking for resistance to ensure the stat was opening and closing the circuit and got a bit of a shock. I think i may of spiked either the PCB on the boiler itself or the timer/stat.

 

[buckers]

1. Its on number 5 of 1-7. Was told that this didnt work and not to use it.

2. The pump runs fine had the inspection screw out and it works on all 3 speeds. Just checked the room stat now and had it set to 22. moved to round to 16 where it clicked and cut the boiler out so looks like that is working fine.


3. Yeah was checking for resistance to ensure the stat was opening and closing the circuit and got a bit of a shock. I think i may of spiked either the PCB on the boiler itself or the timer/stat.

4. there are 2 x 28mm pipes going upstairs but the 2 x 22mm pipes are capped off above the boiler?????
​

 

[Orry Clayton]

How far is thermostat from nearest radiator?

 

[doitmyself]

Can you post some pics?

 

[REDSAW]

british gas been in have they?

 

[buckers]

Hi,
Thermostat is well away from any radiator, British Gas not been near my house. Hope these pictures might help.

Many thanks,

Ian

 

[stevetheplumber]

looks like its a fully pumped system but it may be unishare have a look at the three way vallve head see if it says unishare?

 

[buckers]

looks like its a fully pumped system but it may be unishare have a look at the three way vallve head see if it says unishare?

steve its just got this on it pal

 

[doitmyself]

steve its just got this on it pal

The SD2701 is a mid-position actuator. The person who said 'as my boiler is old the timer needs both water and heating on to allow "heating only" to work', was talking nonsense. The reason you have to have HW on to get CH to work is that the programmer has not been set for a fully pumped system.

Remove the Drayton controller from the wall (loosen screws on underside and hinge upwards). There is a switch on the back which should be changed from G to P.

​

You also need to check that the wiring of the valve is correct.

Turn power off and remove the cover of the wiring box on the floor.

Find the terminal which the grev valve wire connects to.

There should be another two wires connected to the same terminal: one goes to the Programmer; the other to the HW stat on the side of the cylinder.

 

[arran197]

It might be that the mid position valve is not fully motoring over when on CH, thus not turning the CH on when only that is called for. When the DHW is turned on, it fires the boiler, but the water is actually going mainly round the cylinder coil and not really pushing much round the CH side and therefore also giving you your circulation fault?

 

[buckers]

The controller was already set to P but terminal 2 isn't connected is that right? Also took picture of terminal box in boiler cupboard and the grey cable only has on cable extra connected to it as per the right of the picture which runs to the stat on the cylinder. Will post pics in a minute on next thread

Thanks

Ian

 

[buckers]

 

[diamondgas]

Hi buckers - My personal attention would be on circulation as in how well is the water circulating through the heating system. On hot water only the two pipes above the boiler should be relatively similar in temp on a fully pumped system/cast iron heatexchanger. If there's a significant difference (OUCH! one, BRRRR! the other) then you're looking for some kind of blockage/restriction. Bigger the temp difference the more greater the restriction, general rule of thumb 🙂 IMO

 

[buckers]

Hi all,
update......... Stat in room has been changed, spoke to time served heating guy and he popped round two weeks ago. Said he's pretty sure it's the myson aerjec as these clog up and this will be causing the boiler to constantly switch on and off as it thinks the house rads are at tempeture. Week later his young work mate pops round and puts some slush remover in the towel rad. This wednesday( 2 weeks after initial visit) the young lad came, swapped aerjec out and I asked he said it wasn't that bad really. Hooked up power flush for 3 hours, drained and flushed system. Topped up and the issue of boiler still switching off on constant every 5 mins is still there. He left for another job and said he will speak to his boss and I've not heard anything since. The jobs not paid for yet and the lad left all rads fully open hence no rads are really getting warm now. There's allot of bubbling going on as I type directly above there my feed pipe pops upstairs. House is so cold and I'm at boiling point( or not ha ha ha). Please can someone help. Have I really bad circulation and air in this now? Why won't my boiler stay on for more than 5 mins? Young lad said the return might be blocked. The time served fella said originally the return pipe was stone cold and that's the issue. Thanks for reading

 

[buckers]

Quick update, heating on constant but still on/ off every 5 mins. Knocked all upstairs rads off and opened up 3 downstairs a full turn and they are getting warm, far from hot but warmish. Obviously the constant boiler on/off issue stopping them from getting hot. This still a blockage of just really bad circulation hence the boiler switching off all the time? Cheers guys

Ps sat in quiet house and upstairs sounds like a jacuzzi bubbling away,sounds like filling up

pps

been 3 hours now with just the 3 rads on downstairs and yes the boiler is still off/on all the time but these 3 are now quiet warn(not hot)

 

[longboat]

Turn off the boiler. Bleed all rads, pump and vent where the flow goes into the cylinder above the 3 port valve. Turn boiler stat up to full and turn on boiler. after acouple mins turn boiler stat to minimum see if boiler turns off, if not leave at this setting untill it does. then turn stat back to full. if the boiler fires the stat is ok.

 

[secret squirrel]

Didn't you say in an earlier post that the boiler stat wasn't working?

I'm sure you said you were told not to touch something because it doesn't work. I loose track of where I am on some posts. Its my age.

Has that been replaced, surely, if something is not working then thats the point to start?

 

[longboat]

They were told it wasn't working, probs by the same person who told them they had to run HW to get heating. Best to check simple things first. never assume.

 

[lame plumber]

Didn't you say in an earlier post that the boiler stat wasn't working?

I'm sure you said you were told not to touch something because it doesn't work. I loose track of where I am on some posts. Its my age.

Has that been replaced, surely, if something is not working then thats the point to start?

just read the whole story and first thing mentioned was dont touch boiler stat, so id be looking there initially then checking pump working correctly as its awfully like overheating and knocking off all the time

 

[secret squirrel]

just read the whole story and first thing mentioned was dont touch boiler stat, so id be looking there initially then checking pump working correctly as its awfully like overheating and knocking off all the time

Thanks I thought I was missing the obvious for a moment.

 

[buckers]

Hi guys thanks for your input. I checked the boiler stat and it is working. It's only getting to about 3 on the dial but if I turn it below that number when the boiler is on it cuts the boiler off every time. So presume the stat and probe are doing their job