split post: biasi boiler

[dsinclair999]

Hi,
I have a Biasi Garda Plus HE combi M110.32SM/E.
Every time you use a hot water tap (any one) you boiler gives off a loud foghorn type noise, which lasts for approx 10-30 secs!!. It does this with the CH as well, but intermittenly. It appears to happen everytime the boiler ignites if thats any help. The original installer has no idea what the problem is and he's washed his hands off it!!! The gas inlet level is OK and the CO2 level is within the manufacturers spec. The pressure is also correctly set at 1.3 bar as per man spec. This has been going on since it was installed a few months back!!! Any ideas anyone, would appreciate any help on this one.

Regards

DS
_________________________________
lynda, moderator

please note forum rule 20 (I was able to split your post)

 

[clf-gas]

check the flue where it enters the elbow on top of the boiler, i believe you may find that it is not pushed home correctly, found this on a Biasi once with the same symtoms

 

[Agile]

The gas inlet level is OK and the CO2 level is within the manufacturers spec. The pressure is also correctly set at 1.3 bar as per man spec. DS

This is a very common fault and is caused by a weak mixture at low power.

Very few installers seem to be able to set these boilers up correctly for 8.8% CO² at minimum power.

Has your boiler been range rated for a heat output to match your rads which is usually minimum whereas the boilers are supplied set for 24 kW ?

You say the inlet pressure is correct. Can you advise:-

Inlet pressure at minimum power?

Inlet pressure at maximum power?

Pressure at meter at minimum?

Pressure at meter at maximum?

Length and size of gas pipe from meter?

Whats the manufacture date of boiler?

Tony

 

[dsinclair999]

The gas inlet level is OK and the CO2 level is within the manufacturers spec. The pressure is also correctly set at 1.3 bar as per man spec. DS

This is a very common fault and is caused by a weak mixture at low power. Sorry, how do you mean 'a weak mixture at low power'?

Very few installers seem to be able to set these boilers up correctly for 8.8% CO² at minimum power. I do know when the installer spoke to Biasi tech support the min was 8.8% and the max was 9.5%!

Has your boiler been range rated for a heat output to match your rads which is usually minimum whereas the boilers are supplied set for 24 kW ?
Sorry, I don't understand this? I have 4 radiators, 6 sets of taps and the plumbed in shower which incidentally has a very poor flow of hot water, maybe dodgy plumbing!! Plenty of cold mains pressure tho.

You say the inlet pressure is correct. Can you advise:-

Inlet pressure at minimum power? Unknown
I do know the inlet pressure is 19 or 20 using 22mm copper pipe, unsure if this is at high or low power.
Inlet pressure at maximum power?

Pressure at meter at minimum? Unknown, don't think he checked!

Pressure at meter at maximum? Unknown, don't think he checked!

Length and size of gas pipe from meter? 1 metre 22mm copper pipe.

Whats the manufacture date of boiler? Unsure, but I have a small slip of printed paper titled 'Biasi Testing Certification' which specifies a date of 22/02/06 and tested OK!

Tony

Sorry that's all I know and that was with looking over the guys shoulder!!!

 

[Agile]

Perhaps you should put those questions to your installer?

The boiler needs to be rated to power level 1 . Setting can be checked and reset from front panel if you can religiously follow the instructions including the final one to memorise the new setting. Best to recheck setting after memorising.

If I was really convinced all the installation parameters were correct I would tell you of a small mod to fix it. But not without those answers.

At least the short gas supply pipe will be OK but we dont know if the meter regulator is working properly yet. 90% need to be changed when a 35 kW boiler is fitted !

Tony

 

[Paul Barker]

Has your boiler been range rated for a heat output to match your rads which is usually minimum whereas the boilers are supplied set for 24 kW ?
Tony

Isn't it best to leave a small window of operation for the boiler to modulate in, rather than turn it into an oldfashioned on off device? So go right down on the CH power preset (whatever Biasi call it) then back up a small percentage?

Is your mod a tuning hole to change the resonant frequency?

 

[Agile]

The problem with the 32 kW boilers is that their DHW performance is adequate and can almost run two smaller tap flows together and they are ideal for hot water delivery in smaller properties.

The downside is that because there is a limited modulation range of about 3:1 the minimum CH output is about 10 kW which is more than most smaller properties require. Dont forget that heat loss is for an outside temperature at the worst case of -1°C not the current evenings when its 8°C.

So the minimum is more than most properties need even in the coldest weather. The net result is that its back to an on/off boiler. However because the boiler efficiency is so high ( 94% ) thats of limited relevance. So it must be set to the lowest CH output to obtain the best efficiency.

You have guessed it, the mod lowers the "Q".

Tony

 

[dsinclair999]

Hi,

I think the mod has been done already! The installer was told to do this by the Biasi tech support, it involved cutting a 10mm hole in one of the pipes!
Unfortunately can't get hold of the installer or Biasi because of the easter weekend, I was going to call and ask them to guide me thru the process of lowering the preset power rating to the lowest setting. I think it does say in the manual but its not in plain enough english for me!!
Not sure how this would sort the problem with the noise still happening when opening a HW tap even with the CH switched off?

Cheers

DS

 

[Agile]

I dont think you will get anything better than just reading it back to you just as its written in the book!

Its tedious but does work if you can read and understand English!

Tony

 

[dsinclair999]

OK, I'll give it a go.
One last question, is there any way to check what the preset power setting is currently set at?

Thanx again

DS

 

[Agile]

Yes, thats the first thing you should do but it comes AFTER the instructions for setting the power !!!

In the setting mode you have to count the number of times the lights flash !

When it does not do what is expected you have to keep pushing as it says next until the light comes on.

Just to add to the confusion the knob on the left is called "B" and the one on the right is "A" !

Tony

 

[dsinclair999]

Hi Tony,

Ok, done it after a few attempts, the boiler preset for the CH is now set at 10.6, was originally set at 21.0. Unfortunately the howling continues when I turned on the hot water tap. Does this mean the CO2 level will have to be re-adjusted to match this lower setting?
Might it be the meter regulator as you mentioned in your earlier post, is that a gas company thing to check?

Learning loads here, cheers

DS

 

[Paul Barker]

No you haven't done anything to alter co2.

Competent person with analyser must set it up.

Competent person must call transco if s/he thinks their gosvenor to blaim. You ring they will fob you off.

 

[kevplumb]

I dont think you will get anything better than just reading it back to you just as its written in the book!

Its tedious but does work if you can read and understand English!

Tony

patronising ass

 

[dsinclair999]

No you haven't done anything to alter co2.

Competent person with analyser must set it up.

Competent person must call transco if s/he thinks their gosvenor to blaim. You ring they will fob you off.

I realise I haven't done anything to adjust the CO2 levels, and can't without the proper equipment, but I have lowered the preset level to the lowest level and that must surely mean the CO2 level would have to be reset. I assume after my adjustment the CO2 level will now be reading higher or lower than before the adjustment?

Competent person? Where do you find one of them then? My installer doesn't seem to be one, that's for sure!!!! He says his job is done, he's commissioned it and doesn't have a clue how to do it properly, so much for CORGI registration!!

However, looks like I'll have to try and get him back after easter to readjust the CO2 level and hopefully that will sort it, do you think?


Regards

DS

Edit: At least after the adjustment I made it's not quite as bad as it was yesterday, so looks like were're on the right track.