Is my boiler short cycling?

[thomsob]

Hello,

I have a Potteron Suprima 80L installed with my open vented system. The boiler only seems to come on for 1 minute bursts after it has been on for an hour or so. The room stat temp (21 degrees) hasn't been met however, is this short cycling?

The rads in my house never seem to get really hot either, they are def warm and give off heat but certainly not so hot that you can' keep your hands on them type thing.

Any advice/suggestions greatly appreciated.

 

[David937]

What is the boiler stat set to?

 

[D_Hailsham]

I have a Potteron Suprima 80L installed with my open vented system. The boiler only seems to come on for 1 minute bursts after it has been on for an hour or so. The room stat temp (21 degrees) hasn't been met however, is this short cycling?

Are you saying that, after an hour, the house has not reached 21°C?

How long between the one minute on periods?

What is the boiler's thermostat set to?

What room thermostat do you have?

Is this a new problem, i.e the house used to get hot but now it doesn't?

Have any changes been made to the heating system, e.g new or additional radiators, replaced pump etc?

 

[thomsob]

Are you saying that, after an hour, the house has not reached 21°C? - Yes, after 3 hours the house still isn't at 21 degrees. In saying that the stat is in the hall which is the coldest part of the house as it is only served by one small rad. The bedrooms up the stairs definatly don't get near 21 degrees though. I think the living room might get near that temp, it is served by one 1200 and one 1000 K2 radiators.

How long between the one minute on periods? 4 minutes. When the boiler is on the red temperature light comes on just before it stops.

What is the boiler's thermostat set to? - I'm not sure how to check this, can someone tell me please and i will check?

What room thermostat do you have? - I'm not sure what is being asked here exactley. The stat is made by honeywell and has a dial, it looks pretty old.

Is this a new problem, i.e the house used to get hot but now it doesn't? - No, i moved into this house 2 months ago and the boiler has been like this always. To tell you truth i though it was normal as my previous places have had storage heating.

Have any changes been made to the heating system, e.g new or additional radiators, replaced pump etc? - No, nothing changed

 

[D_Hailsham]

How long between the one minute on periods? 4 minutes. When the boiler is on the red temperature light comes on just before it stops.

That's the lockout light.

The boiler is fitted with a safety thermostat to protect against overheating of the water. If it operates, the boiler will lockout and the LED will flash red once a second. The boiler will need resetting before it will re-light. If the control does not reset, leave the boiler to cool down for approximately 15 minutes before pressing the reset button again.

I moved into this house 2 months ago and the boiler has been like this always.

Definitely not normal. The boiler is overheating and locking out. There could be several causes, e.g faulty pump, faulty motorized valve, boiler thermostat faulty etc. Post full details of your system, i.e make and model of all the components, so we can advise what/how to check everything.

 

[WDIK]

delete

 

[thomsob]

I'm not sure if it locking out, but i'm no expert. Reason i say this is that i don't have to reset anything once the red light comes on. It doesn't flash either, it just stays lit, then the green light below flashes and it comes back on.

The boiler itself is a Potteron Suprima 80L. The pump being used is a Motorhead III, supplied by British Gas. There are also 2 zone valves. The system has 8 rads all fitted with TRV's, and a towel rail which i think is served by the hot water tank.

Is that enough detail to go on?

Thanks in advance.

 

[thomsob]

Further to this all my rads seem to get hot, but like i said earlier i don't believe they are getting as hot as they should.

The pump seems to be working as when i turn the room stat down it clicks off (normally at about 18 degrees) and i can hear something click under the stairs, which is where the pump, zone valves and water cylinder are located. I assume there is a more technical way of testing the pump out however

 

[D_Hailsham]

The boiler itself is a Potteron Suprima 80L.

What is the GC number?
What is the Boiler Code number?
Are the green and red lights separate or is it one light which changes colour?

 

[thomsob]

GC 41 590 47
Boiler number LVM034300302BP

The red and green lights are separate.

Once the boiler has gone off due to the red temperature light coming on, i noticed that the green light keeps flashing. Didn't notice this before.

 

[D_Hailsham]

Once the boiler has gone off due to the red temperature light coming on, i noticed that the green light keeps flashing. Didn't notice this before.

This is normal as it means that the boiler has reached the temperature set by the boiler thermostat. So it's not a lockout.

You asked earlier how to check the boiler thermostat. It's the knob next to the LEDs marked from OFF to MAX. Where is it set to at the moment? (e.g 11 o'clock, 2 o'clock etc)

 

[thomsob]

The dial is set to max, which is about 5 on the clock.

 

[D_Hailsham]

The dial is set to max, which is about 5 on the clock.

Then I can't suggest you turn it up to max.

So your boiler is getting up to temperature, switching off, cooling down and, about four minutes later, it turns on again. Nothing wrong with that. BUT your house does not get up to temperature.

The symptoms you describe can be caused by having a boiler which is too big for the radiators. Yours is an 80,000BTU or 23.4kW boiler. Which is on the large size for a regular (not combi) boiler. Do you live in a large house with a considerable number of radiators?

If you have the time, use the data in the Stelrad Elite Catalogue to calculate the total output of your radiators and compare it with the boiler output.

 

[thomsob]

I stay in a mid terraced that comprises off a large livingroom/dining room, average sized kitchen, downstairs WC, updatirs bathroom and three bedrooms, 2 are double one is single in size.

Each of the bedrooms have 800 K2 rads, the kitchen the same. Towle rail in the bathroom, 1000 K2 rad on the stairs landing and a 1200 and a 1000 K2 in the livingroom/dining room.

Does that help?

 

[thomsob]

I have worked the outputs from the link you supplied (thanks very much).

It comes in at 40,646 BTU.

This backs your theory on the boiler size.