Baxi off and on

[balls]

Though our boiler works, it does so inefficiently.
When we increased the temp by turning the Central Heating Temp Control to max' in November last year we noticed a change in the boiler's actions.
When the boiler is switched on the 'Burner On' indicator lights up and the water temp increases as shown by the 30deg - 80 deg indicators. The sound of the boiler is evident but is accompanied by a fast ticking noise. The 'Burner On' indicator and boiler itself go off after 2-3 mins and the temp indicators show a decrease in temp as one would expect. After 3-4 mins of inactivity, the boiler restarts.
The boiler functions in this way for anything between 12-15 hours and then appears to stabilise without any further cutting off. In other words the 'Burner On' remains on and the temp gauge shows a constant 80 degrees.
Whilst this is irregular and may be causing greater bills than necesssary one of the most immediate problems is the ticking noise from the boiler.Each surge caused by the boiler switching on causes the aforementioned ticking at the boiler.However this then affects 4 radiators ,which 'tick' incessantly, as the surge passes each one in turn-every 3-4 minutes for 12-15 hours until the boiler remains constantly on.
Our boiler was fitted last year, Feb 17th and had the obligatory 'Flush'.
Thus we do not suspect a block at 4 radiators on 3 separate floors.
Further, when the boiler finally remains on, after 12-15 hours, the ticking at both boiler and 4 radiators ceases.
Any suggestions

 

[chrishutt]

Our boiler was fitted last year, Feb 17th

Well it's still under guarantee so get the installer or boiler manufacturer onto it pronto. It sounds as if the burner is failing to modulate as it should.

 

[ChrisR]

It's still under warranty, why not call the installer - who will doubtless tell you to call baxi.
It would be interesting to know what boiler you're talking about.

 

[balls]

Good advice.
It's a Baxi Combi 130 HE

 

[balls]

My installer came out today and said that's how the boiler functions and that when the boiler thermostat reaches a certain temperature it cuts out. I queried the fact that it did this every 2-3 mins and that after 12-14 hours it remained on -constantly until I switched it off.
He went further and said the ticking noises at 4 radiators, which only happens when the burner fires-up each time, is caused by pipe expansion.
I asked if the pipes would need to expand every 3-4 minutes.Surely one expansion would be enough and this would only happen if the burner stayed on like it does after 12-14 hours.
He's arranged for the supplier ( BAXI)to come out next week and is adamant he will ' echo' his views.We'll see.

 

[Paul Barker]

Gasthepottyengineer will know best, but here's my halfpeneth worth.

Good basic design that boiler.

BUT I don't think it is of the type which modulates ultra cleverly, so it might well run in cyles on and off. The best way nowadays is to keep going ever so little most of the time as final room temp is reached. Your boiler cannot be adapted to do so, it is a design feature of the very best boilers involving the coordiated activities of the room thermostat pump speed and modureg.

There would probably be adjustment on the pcb for the timing of the anti short cycling feature of the design (which is not proved to be energy efficient, though a boiler has so many on off cylcles worth in it, and it has been muted that a boiler which is on most of the time would last longer than one which is frequently cycling).

Why it stays on ad infinitum sounds like a fault.

Pipes creak every time they heat up, they contract when they cool, they then creak again when they heat up, ad nausium.

Sounds like a good job heatteam are coming, they are great blokes it's a sound boiler and they should get you sorted out.

 

[balls]

Thanks for the reply and your confidence in Heatteam.

 

[Paul Barker]

No problem, I also have confidence in the boiler and that it can be resolved.

You may however have to get used to the ticking noises from the pipes.

I had a customer recently called me back to listen to his heating.

Darn it, I did such a good job of powerflushing his completely sludged up pipes he didn't realise that when they aren't damped by a thick layer of sludge you can hear the water in the pipes.

I told him he was going mad hearing things that everyone else hears but apreciates is a small price to pay for having a warm house.

I think he still likes me 'cuase he passed my details to his dad to service his boiler and fire. Never can tell though if my speak as you find approach hasn't been misread. People have a propensity to take a chap the wrong way in this day and age.

 

[andsam]

When the boiler reaches temp the burner goes off and so does the pump. After approx 3 mins it brings the pump on and circulates the system water.The boiler then reads the system temp and decides weather it needs to refire the burner or not. This could be the reason you do get some noise from the rads.

Do you have a room stat?

 

[ChrisR]

I wouldn't have thought the boiler would take 12-15 hours to stabilise. Do you have a baxi "intellistat" on the system or a standard thermostat?

Oddly the Baxi literature does not give a minimum output for the 130HE (and the lit is NOT on the partsarena site). It does for the 105HE, at 11 kW. Once your house is warm it's unlikely that it would be needing 11kW just to keep warm, so something sounds wrong unless the (later) 130HE goes lower.
Try turnng the CH temperature down, just to see what happens to the creaking, but also most people don't want their radiators that hot.

The creaking is either pipes rubbing against the floorboards, or the radiators moving against the rad brackets. If the latter, short pieces of 6mm earth bonding cable, bent into an inverted V, can be dropped onto the top hook and the rad lilfted slightly to let the cable drop in. Then the rad slides along the twisted copper, once through the plastic, and it doesn't jump making a noise.

 

[balls]

Thanks for the info.
andsam- no room stat
chrisR- have turned down but still cuts out and restarts over many hours.