combi boiler and log burner


Postby mattstan » Fri Oct 03, 2008 8:51 am

hi everyone,

can anybody please give me advise?

i know diddley-squat about heating sytems!

i've just had a worcester bosch 30cdi fitted...

i've also got a hunter log burner...with a built in back boiler

they are both connected to the central heating system, i know this because the hunter warms up when the radiators come on. i haven't tried lighting the fire yet, in fear of it ruining my new combi boiler

can i use the hunter to compliment my combi?

i value any input
mattstan
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Postby htg engineer » Fri Oct 03, 2008 8:31 pm

The log burner does not have a thermostat, so when the combi thermostat kicks in and shuts the boiler down the log burner will still be heating the system.

Excessive heat with the fan and pump not running could damage parts of the boiler.


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Postby mattstan » Sat Oct 04, 2008 11:27 pm

thank you for your help, i'll have to have a re-think.

as we still would like to use the fire, any suggestions?
mattstan
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Joined: Fri Oct 03, 2008 8:19 am


Postby plumbbob » Sun Oct 05, 2008 12:11 am

Htg, I would say with the combi pump shut off because of a no call for heat, the water in the back boiler would boil causing a potential explosion risk and damage to the combi at the very least, especially as any water boiled off is not automatically replaced.

As far as I am aware, all solid fuel heaters with back boilers can only be run when coupled to a gravity fed system with a hot water storage tank. This ensures the water will continue to circulate even in the event of a mains power or component failure.

Extra consideration should be given to the increased risk of water boiling with solid fuel heaters.

My guess is, whoever installed the combi didn't realise the log burner had a back boiler!! Wow.
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Postby htg engineer » Sun Oct 05, 2008 6:40 pm

Htg ?? it's mattstan asking the question.

The PRV would open though as the pressure built up, so probably no explosion.


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Postby plumbbob » Sun Oct 05, 2008 10:54 pm

Sorry Htg, just meant to add to your useful post by commenting to you. No criticism was intended but I believe there could be a real danger of damage to the system. Yes you are right the PRV should operate and avoid an explosion, but with the continually reduced water level and the PRV located far from the back boiler, would it be worth putting any money on it?

What is important is to get a second opinion about the inclusion of a log burner being connected to a pressurised system with a standard combi as I cannot see how it can work.
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Postby htg engineer » Mon Oct 06, 2008 4:15 pm

I didn't think you were criticising, just wondered why you were addressing your post to me and not Mattstan.

The log burner should not be used, in conjunction with the combi. That's what I intended Mattstan to take from my post (like to keep them short).

I'm very surprised that the log burner is connected to the system, hopefully the installer didn't realise and it wasn't intentional.

Also if it's an old log burner i'm surprised it's not leaking with this being a pressurised system, and the log burner was/is probably full of debri's - now in the combi !!!! many breakdowns in the near furture I think.

sorry for any confusion


htg
htg engineer
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Postby mattstan » Wed Oct 08, 2008 9:00 am

thanks for all of your answers, i'll get it disconnected asap
mattstan
Posts: 4
Joined: Fri Oct 03, 2008 8:19 am


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