short cycling caused by the boiler getting too hot

[chris_maddison]

OK its short cycling caused by the boiler getting too hot... Can you turn more radiators on ??

How can i fix this

 

[sterose]

Reduce the heat input to the boiler or, yes, turn more radiators on.

One radiator turned on, will not reduce the temperature of the water in the system that much, so the boiler gets too hot and turns off.

 

[chris_maddison]

I have a swith 0 - High or Low at the moment it is set to low. Is this where I reduce the heat?

Sorry If silly question, I have only brought my first house and this is all new to me.

 

[sterose]

Reduce heat input:- I know I can on my boiler, but it involves fiddling around with the settings inside the boiler - its supposed to be for the plumber to alter, not the user.

But I would reccommend just turning all radiators on all the time, and then it keeps your whole house warm.

 

[GarryK]

I've had my boiler Ideal H24 short cycling. Every few seconds the fan starts then stops. The only thing is I closed down the lockshield a few turns on the bathroom towel rail radiator. As soon as I opened it up a couple of turns the boiler has gone back to normal working.

 

[Mottie]

After 21 years, the OP has either sorted it or replaced it by now.

 

[ericmark]

There are two basic types of boiler, modulating and non modulating and the latter is designed to cycle. Mine is the latter and turning the boiler temperature up increases the time between start of each cycle.

Last house had modulating boiler, and the radiators were really too small, theroy is great, one is expecting to get home at 6 pm, so 5 pm the kitchen starts to heat up, then 5:15 pm the dinning room starts to heat up, followed by the living room at 5:30 pm then bedroom at 9 pm. The idea is the kitchen radiator is really hot before the dinning room starts to heat, so rooms heated faster and in the order used.

But in practice it does not work that way, as to why wish I knew, but seems to work better when all three rooms down stairs heated together.

But every home is different, last house modulating boiler, so set the lock shield valves by looking at the TRV report. Easy enough if a TRV reports the current is above the target, then clearly the lock shield needs closing, and visa versa, and I got the house so each room was spot on. Thought great, know how to do this now, moved to this house, and did not work, basic all lock shields wide open.

However last house it was having lock shields wide open which caused the cycling. Yet this house the reverse is true. But the basic idea is as each TRV closes it first forces more water through those still open, and then lifts the by-pass valve, so as the home warms up the return water should get warmer and warmer, which with a modulating boiler causes it to reduce output, and then when it can't reduce output any more, it starts to cycle.

But this has not always been the case, before the advent of the modulating boiler we would have one radiator with no TRV (normally bathroom) so there was always a path for water to circulate, but with the by-pass valve this allows hot water to return fast to boiler if all TRV's are closed, and the speed taken is used by many boilers to set the algorithms that set how long the boiler should remain off, before restarting, referred to as anti cycle software. And having a wall thermostat can mess up the boilers algorithms if it is simply on/off.

Many boilers have been replaced without changing the plumbing, so in many cases the installation is flawed, even the boilers instructions often say don't fit a TRV in the room with the wall thermostat, they also say wall thermostat should be in a down stairs rooms (heat raises), with no alternative heating (this includes sun through windows), kept cool (as don't want CH to fire up when likely going to be a warm day), and no outside doors. Well my house no such room. So wall thermostat in hall, but also a TRV on hall radiator to allow quick recovery when front door opened, but stops hall getting too hot so stopping rest of house getting warm.

Everyone has their own idea as to how to control the heating, non are either right or wrong, just different. It depends on not only the house, but also life style. Second house I had in living room a standard radiator, a fan assisted radiator, and a gas fire, no need for geofencing as room heated up that fast, this house also no point in geofencing due to reverse, living room heats up too slowly need heating on three hours before using room, and clearly if you are only in the house 12 hours a day, you want fast recovery, but if retired like me, just never turn heating off.

So you need to find what suites your house with your life style, short cycling may be what you need?

 

[jurassic sparkk]

Sometimes I just wonder.

 

[JonathanM]

To be fair, when you come to post a new topic, you are asked "Is this already being discussed" and are given a drop down list of possible threads to choose from. It is confusing at first for a new member.