Halstead Ace Combi Boiler - Hot water cuts off

[d24_7]

Hi
I've had problems with the hot water on my Halstead Ace Combi Boiler for around 6 months.
It started with the boiler locking out during long run off's of hot water.
Then around 2 months ago I noticed the baths were cooler. On investigation I found the burner would only stay on for around 1 minute when running hot water, the burner would then turn off for around half a minute and then come back on. This process repeated until you stopped running the water.
Now the burner only stays on for around 10 - 20 seconds before going off for 30 and so on.
I've tried replacing the DHW Thermistor but this hasn't helped.
I believe the problem could either be the DHW heat exchange or the PCB but need a second opinion or a way of testing for which one it is.

Thanks in advance

 

[webrits]

There's a fault finding guide HERE for these. May help you. See page 27.

 

[d24_7]

Thanks Webrits.

The flow charts would appear to only help if the power / ignition wasn't working at all.

The burner on my boiler only goes out during hot water run offs. The central heating works ok.

Something I did neglect to mention before was the flow switch and the Auto Air Vent was changed about 9 months ago. Don't know if that will help.

 

[Terrywookfit]

Check the DHW heat exchanger for cr~p!

 

[d24_7]

Check the DHW heat exchanger for cr~p!

I'm not judging your ability, I'm just one of those REALLY annoying people that needs to understand why he's doing something.

Why, does a blocked / clogged / dirty DHW exchange cause the burner to turn on and off as it is doing?

In the DHW mode diagram on page 7 of the manual, I can see that hot water is pumped from the main heat exchange and diverted through the DHW heat exchange. Presumable, as the name suggests, the heat is exchanged to the cold water pipe on the other side of the heat exchange and hay presto, hot water.

 

[Terrywookfit]

The boiler fires and tries to dissipate the heat produced into the Dhw exch!

Due to blockage in the primary side, it is unable to and so turns off until the water has cooled!!

Obviously the H/E is not completely blocked as the flow switch is operating!!

 

[Agile]

I'm just one of those REALLY annoying people that needs to understand why he's doing something.

Why, does a blocked / clogged / dirty DHW exchange cause the burner to turn on and off as it is doing?

In the DHW mode diagram on page 7 of the manual, I can see that hot water is pumped from the main heat exchange and diverted through the DHW heat exchange. Presumable, as the name suggests, the heat is exchanged to the cold water pipe on the other side of the heat exchange and hay presto, hot water.

Unfortunately I do find it annoying when an owner still asks that question when he clearly is unable to understand how the boiler works.

Its not necessary for you to understand how the boiler works to fix simple problems.

Surely you could have deduced from your bold quote that if the heat exchanger is blocked the heat is NOT going to be passed into the hot water. The boiler cannot carry on supplying heat which has no where to go so it gets too hot and turns off the burner.

The dirt is as a result of a cheap or cowboy installer who has not properly cleaned the system.

Tony

 

[d24_7]

Agile, That was a very arrogant way of saying the same thing that Terrywookfit managed to say in a very professional manner.

Tut tut Agile.

Well done Terrywookfit, and thank you. The explanation was very helpful

 

[Agile]

I was trying to say that you dont need to know why that happens but even so you should have been able to think a little more and deduce why if thats so important for you.

You only really need to know where the problem lies and how to deal with it by replacing or cleaning the secondary heat exchanger.

Tony

 

[d24_7]

Apology accepted.

I'm going to check the DHW exchange and will clean or replace as appropriate.

I'll let you all know how it goes.

Thank you all for your help so far.

 

[d24_7]

Hi all,
IT WORKS!!!!

Fantastic. Hot water never felt soooo good.

The DHW heat exchange (primary side) was full of black scaley stuff.
I cleaned it out as best I could and put the boiler back together in order to at least get the CH back.
If the DHW didn't work then I would have gone to my local PTS tomorrow and got a new DHW heat exchange.

Thank you everyone for your advise.

Does anyone know of a way to stop the heat exchange getting like that again?

 

[Agile]

Power flush or chemically treat the system, fit a line strainer in the return, fit a Magnaclean plus a filter washer etc.

Tony

 

[buggslife]

Been reading up on posts with a similar problem to me and would like to clean out the 2nd heat exchange...attached some photos.

Untitled

• buggslife
• 10 Aug 2011
• 2

Untitled

• buggslife
• 10 Aug 2011
• 2

Can anyone help explain how to clean it out?
Also, do the areas of limescale at the joints suggest build up inside?

Thanks.[/img]