Worcseter 440CDI hot water temp varies

[timdf911]

Hi guys,

Sorry for the length of this post, but I've just had a W-B 440CDI boiler installed, on paper and from reviews it seemed just the job to heat and provide hot water for my 4 bed detached bungalow.

The guy who installed seemed to do all the right stuff, like flushing the system etc and followed the installation instructions.
FYI we have a static water pressure of 2.5B and a flow of 22l per minute.

Water temp control on boiler is set to 4

Problem is the water temp at a hot water tap near the boiler cycles between 36C and 62C - even though the flow rate is only 7l per minute.

It does this within a couple of minutes of turning the tap on ie after about 15l - no where near the 51l or 20l / per minute flow rating.

I also notice the temp on the boiler goes as high as 112 !

There's also gurgling and bubbling noises coming from the boiler.

I suspect the heat store is not filling correctly.

As a consequence even the show goes from luke warm to scalding hot.

Any ideas or suggestions ?

Thanks Tim

 

[St0rmer66]

What does the pressure gauge on the front of the boiler show? If it's low then it might just need a top up. If it's fine then it just sounds like there is air still trapped in the boiler which hasn't been bled. Installer should have done this but even with the best will in the world, some can be left in and airlock later. If you trust him then get him back to sort it I'd say. It's not something he should be charging for though.

 

[timdf911]

The pressure gauge reads just over 1 bar and is steady at that reading.
I agree it's most likely not fully bled, plus there's air in the upstairs radiators.
So I'm hoping a good 'bleeding' session might sought it out.
He's coming back later today to get paid - so I'll mention it then.

Thanks for the advice.

 

[St0rmer66]

To clarify further, the air is the most likely cause of the lack of circulation around the boiler, hence the high temperature readings and lack of heat transfer. It's not the "only" reason but the most likely if he's flushed it properly etc to remove physical blockages. Should be a quick job if that's all it is. If you're comfortable bleeding the radiators and topping up the pressure yourself you might be able to sort it before he arrives but if not then leave it to him.

 

[timdf911]

I could bleed them myself as it's a straight forward job and he's shown me how to do it.
But for now I'll let him take care of it.
So I assume the excessive indicated temperature and the rapid rise of said temp is associated with excess air ? Seems logical.

 

[St0rmer66]

Diagnosing over the Internet is not a perfect science but yes that's what it sounds like .

 

[Tony13579]

I has a new WB boiler.
3-4 months later it varied the shower temp.
I called back the installation team.

It turned out to be crud in a very old regulator in the gas meter box.
Gas networks turned up and first worts were is it a woucester ?
Gas starvation seams to be a regular issue.

New regulator and correct adjustment of that regulator solved it.

When they installed it they upgraded the copper gas pipe from 15mm to 30mm

 

[St0rmer66]

I has a new WB boiler.
3-4 months later it varied the shower temp.
I called back the installation team.

It turned out to be crud in a very old regulator in the gas meter box.
Gas networks turned up and first worts were is it a woucester ?
Gas starvation seams to be a regular issue.

New regulator and correct adjustment of that regulator solved it.

When they installed it they upgraded the copper gas pipe from 15mm to 30mm

That wouldn't causing gurgling and overheating though! But a common problem; on new and existing installs, when the regulator is old.

P.S. It'll be 28mm pipe .

 

[timdf911]

During the install the engineer checked the gas pressure and pipe sizes etc plus our gas meter is relatively new (<3 years old) so I doubt it's gas starvation in this case.

But as St0mer66 says - remote diagnosis is not a perfect science, however in this case I suspect he's correct and it is air in the system.

Installer didn't turn up to collect his payment and bleed the system again so I guess it'll be tomorrow before we know for sure.

BTW I can understand how bleeding the rads work, but if the diverter valve is set for DHW only and there is air in that circuit / heat store I wonder how to get the air out short of using the bleed valve on the pump which would seem to be too low in the circuit (air rises etc).

 

[St0rmer66]

Turn the heating temperature down to "1" and put the heating on . You may even find that turning on the heating for a short period pushes the air round into the radiators and allows the hot water to then work fine. Usually the first thing I try if a boiler is air locked. It's a lot easier to bleed it from the rad's than the boiler itself usually.

 

[St0rmer66]

Alternatively there is an "air purge cycle" which the boiler can be put into using the service functions which is fairly easy to do, if you're feeling confident (it just requires pressing buttons on the front).

 

[TCCHeating]

There is an extra auto air vent on the top of the water storage tank. Make sure this is open

 

[timdf911]

Thanks TCC Heating - sounds like the ideal solution.

Still waiting for the installer to come over - I'll mention that to him.

Did try the service level 1 air purge program but didn't seem to make much difference.

 

[timdf911]

TCC - quick question.

This air vent on top of the water storage tank, would this be the black plastic device about 2" tall and 1" diameter ?

If so what do you do with it ?

I suspect my installer is a little 'green' when it comes to this model of boiler and I want to point him in the right direction

 

[TCCHeating]

The 440cdi is a storage combi, (think previous posters may have overlooked this )

On the left hand side of the boiler is a storage tank, it is wrapped in foil insulation, on top of that tank at the highest point should be an auto air vent. I can't remember if it's plastic or brass. But it will have a cap on it similar to a car/bike tire. Make sure it is open (ie that it is loose, you can turn it freely by hand)

Ps. It should always be left open