Boiler cycling on /off every 2 mins when heating

[ElCI]

Sorry Hugh, in regards to your question, yes those 2 pipes feed the cylinder, it's not so much a ceiling they're going through but a partition in the cupboard, see the picture below

Also yes I have an open vented system, not however that the pipework on question stops at the cylinder and therefore does not continue up to above the fill and expansion tank.

No luck getting an engineer out yet. I do have homecare so might try that although I suspect they're more setup for boiler repair as opposed to central heating issues. Also I have tried turning what I assume is the bypass gate valve down by a turn to see if it helps

 

[Agile]

You should close the bypass valve and count number of turns.

Then open exactly one turn.

Tony

 

[ElCI]

Tony, I'm happy to do that, I have actually closed it by 1 turn now anyway, are there any risks to doing this? I understand the bypass is there for safety so the fact it has been left fully open is why I'm a little apprehensive about closing it any number of turns

Thanks

 

[Hugh Jaleak]

Get system changed to S plan, relatively easy to do, (you already have a valve on CH, so need an additional 2 port valve on HW, cylinder stat and someone to wire it all up.

 

[ElCI]

Ok, cheers , I've had difficulty getting hold of a central heating engineer so iv put it on mybuilder and I'll taken it from there.

 

[DP]

Ok, cheers , I've had difficulty getting hold of a central heating engineer so iv put it on mybuilder and I'll taken it from there.

i would suggest you close the bypass valve completely.
the valve to cylinder closed till ch and he returns are similar temperature
this off course when cylinder cold as hot cylinder return will always be hot

some good guys in Lanarkshire. Whereabouts are you

 

[Agile]

No significant risk to close to just one turn.

Tony

 

[ElCI]

i would suggest you close the bypass valve completely.
the valve to cylinder closed till ch and he returns are similar temperature
this off course when cylinder cold as hot cylinder return will always be hot

some good guys in Lanarkshire. Whereabouts are you

Hi DP, that sounds like a good method, generally speaking I don't like changing these sort of things as it's not my area of work but I think I'll give it a go. Can I clarify a few points tho
Would you leave the bypass closed permanently? I was going to take Tony's advice and reduce it to open by 1 turn
Re the hw cylinder, so basically drain the hot water until the cylinder is full of cold water then turn the boiler on and close the gate valve (located on the return pipe) until the temperature of the CH and hw return pipes are similar?

I'm in cumbernauld, if there's anybody you'd recommend I'd happily pay someone who knows what they're doing to come out and do this for me. Also, I'm pretty keen on getting a switch fitted so I can run ch only

 

[Hugh Jaleak]

My two penneth again. The bypass is pretty irrelevant at the moment, as the cylinder coil will always allow some flow through the system with the present setup. (Closing that gate valve on the cylinder circuit will prevent the cylinder from being heated by the boiler so you'd have no hot water.) Close the bypass totally, and then you need to regulate the gate valve on the cylinder circuit as DP has suggested.

I'd do this with the cylinder as is, if the cylinder is cold the heat losses from the coil would give a lower return temperature, and therefore you'd open the valve further to try and balance it out with the CH, which is rather defeating the object.

Ideally I think you want to keep flow through the cylinder to a minimum to push more of the flow through the CH system. Often gate valves are fitted, or the pipework reduced to 15mm, on the return from the cylinder on fully pumped systems to try and prevent the cylinder robbing the lions share of the flow when HW and CH are on simultaneously.

 

[DP]

I would close the bypass completely for present. No need to pass any flow through the bypass the set up you have at present

JH hit the nail on the head

Ian, puller, Tony, a few others. I am in G61 area and have a few clients in your township

 

[stem]

All Baxi Solo's 2 and 3 that I have seen (including my own) have always worked like that. Despite its name, a boiler shouldn't actually boil the water, so the boiler will go off when the water inside it reaches the temperature set at the boiler thermostat.

If the water leaving the boiler outlet pipe is hot, then the boiler is doing exactly what it should do and is controlling the temperature of the water it provides.

More modern boilers achieve this by modulating the flame so that it goes up, or down according to the demand. The old Solo's achieve the same thing by turning the burner on, or off, and this is how they work.

 

[ElCI]

Hi stem, yeah I'm confident the boiler is working properly, it's more the heating system /pipework in general I'm concerned about. When the cycling starts the radiators have not properly heated up on the other hand my hot water would melt the skin off your hand! So it seems that there's an issue where the water from the boiler is basically just circulating through the cylinder and back to the boiler, causing it to reach temperature when in fact the heating is still relatively cool.

1 other thing to note about all this is that even though the gate valves appear to be wet wrong, I am confident that this issue only started when I had the system drained down recently so I'm not sure if there's anything else affecting it, my guess is possibly a blockage in the CH pipework. I was actually woken up last night by the radiator in my room, when the boiler turned on there was all sorts of noises coming from the lock shield valve, a sort of popping /cracking and hissing sound, loud enough to wake me up. I'm thinking about trying to get another heating engineer out to put a cleanser through the system for maybe a week and then drain the system down again and try and remove any blockages, DP, HJ, tiny etc would you think this is worth doing in addition to the gate valves?

Thanks

 

[Hugh Jaleak]

All I can think of is the guy that came last has opened that gate valve on the cylinder circuit a lot wider, which is causing the lions share of the flow to go through the cylinder, whereas previously it may have only been open a crack. System will need to be drained to cut a motorised valve into the cylinder circuit, so I'd do the lot in one go. No amount of fiddling is going to result in any drastic change, until you get proper control on the cylinder circuit.

Have you tried closing off the gate valve on the cylinder and forcing the full flow round the rads?

 

[Agile]

You seem very reluctant to try dimple adjustments.

Close the bypass, either completely or to just one turn open.

Then close the cylinder valve to just one turn open.

Then see what the rads do.

Tony

 

[ElCI]

Hi all
1st off I'd like to say thanks for all the help so far, I know I'm a bit of a nightmare when it comes to this sort of stuff but it probably stems from the fact that I'm an engineer myself and I've seen 1st hand the dangers of messing about with stuff you don't fully understand!

Anyway, I have put an update below on the results of what you have recommended, it's a bit long winded but I tried to cover everything, again I'm very grateful for the time people have took to help me with this.

I tried what you recommended, I turned the bypass fully off and turned the cylinder valve down to 1 turn open. It seems that this worked, the boiler ran for 30+ mins without issue. During this time there was a noticeable rattling sound coming from the bypass gate valve. I also opened up the lock shield valves in the radiators that have been having issues. During this time the CH return pipe was hotter than it has been the hw return was cooler,the bypass was still hot but I suspect that this mightve been because I did run the system with the bypass open for the 1st 5-10 mins.
I then experimented a bit by opening the gate valve, within a few mins the boiler began cycling again. Although this is a limited test and I'd probably need to do it again to confirm things (it should be noted that my wife had ran a bath and used up the hot water in the cylinder so I suppose the fact that it was full of cold water would've prevented the return from heating quickly?)

I still have it in my head that this bypass is a safety related item, in don't fully understand why it's there to be honest as a direct link between flow and return right next to the boiler seems a strange idea to me. Since I am put the house most of the day and my wife and daughter are in here I decided to play it safe for now and take Agiles advice of leaving the gate bypass open by 1 turn, the rattling got worse at this level though so it is probably 1.5-2 turns open now, I'll see how the heating goes at this level. The other thing I noticed for a fair bit of noise coming from the cylinder once the room thermostat had reached temperature and the boiler had stopped, it was a sort of water bubbling/boiling noise.

I have also took hughs advice and am waiting on a quote for changing to a S plan system, I have also asked for a price to fit an automatic bypass valve as I assume this will solve my issue of wanting it to be closed normally but be open when required.