831 on micro bore

[E4gas]

I fitted a vaillant 831 to a micro bore system , chemical flushed system with new rads added .
The boiler fires up , runs for a little while heats up rads ten shuts down , boiler only been fitted for 7 days ,
Vaillant engineer went out to check boiler and said it's to powerful for micro bore system ,
He recommends me changing boiler to a gloworm ,, any one else had this problem with vaillant & micro bore

 

[Kev the gas]

Id love to see a copy of his job report !

Did he suggest a lower rated boiler ?

Kev.

 

[AWheating]

whats the heat output of the radiators?

 

[E4gas]

He adjusted the kw on the boiler , he said on the phone , also said to much inhibator in water , the job is 60 miles away from me , in a old ladys house . I left pressure on 2bar , she rang me today to say pressure has been dropped to 0.7 bar ,, now the boiler not happy , as mi say no less then 0.8 .. And she won't turn valves to top up ,,

 

[anz]

Whats the return temperature your getting?

 

[Billy Bob Bob]

to powerful for minibore?????????????? what a load of rubbish,i must have fitted thousands of 10mm drops with no issues and quite a few on 40kw duotecs valiant engineer is a numpty

 

[Nostrum]

When you say shuts down, do you mean lock out, or stop's firing and continues to circulate?

Also, why 2 bar?

831 has a minimum output of 6.8kw (I think) and can be rated down to either 9 or 12kw max through the boiler settings.

At worst it would just short cycle and run fairly inefficiently I would have thought. How may rad's? No idea how he could tell you added to much inhibitor, can't win it would seem!

 

[E4gas]

My lad put 2 bar in , as boiler mi said between 0.7 - 3.0

7 rads on system , all doubles,, 6 honeywell TRV fitted

 

[E4gas]

At worst it would just short cycle and run fairly inefficiently ,, that's what he said , the return temp is near the Torrance off the flow

 

[E4gas]

I don't like to power flush Micro bore system , but might to before I change boiler ,, gutted as I fitted vertical flue though roof as well

 

[Nostrum]

What did you replace?

Have you balanced the rads for a 20 degree drop across flow and return?

If the pipe work was causing too higher a resistance the return wouldn't be coming back that hot unless the bypass was letting by to easily. I've got an 831 at home rated right down to minimum and it works fine, albeit not ideal as my houses heat loss is probably about 5kw/hr.

What was the reason for getting vaillant out? Did it lock out?

 

[E4gas]

Old lady not happy as boiler would heat up then shut down . Took out a old 155x thermo store that did not work ,, I have not balanced the rads 20degree , as system worked fine when I'm there , it lasts about 1 hour then stops ,,

 

[stevetheplumber]

the bit about the boiler being to powerfull sounds like BS We have fitted loads of vailants with 10 mmm micro bore manifolds realy need more info is it cycling or locked out ?

 

[TBServices]

Sounds like you need to go back to job if basing the "problem" on the word of an old biddy.

 

[Nostrum]

Room stat satisfied? Trying to explain that radiators will go cold when not required is like :banghead: Sometimes with the older generation

 

[kay-jay]

Had this twice on the 831 All i did was drain and re-fill. Something to do with a sensor. Apparently its quite common on the new models.

Sent from my GT-I9100 using Tapatalk 2

 

[stevetheplumber]

Ive had similar on a heat only where the flo and return cant be to close in tempretureis resistance in the system opening the bypass?

 

[E4gas]

I went back today , I turned it on , rads got red hot quick ,I left lady happy ,,
Tonight lady rang said worked for 1 hour then shuts down , honeywell TRV on all rads but one , the one stays hot ( bypass) .. Longer

 

[TBServices]

Room stat satisfied? Trying to explain that radiators will go cold when not required is like :banghead: Sometimes with the older generation

Sounds like this is the problem.


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[Roger Welton]

'Customer gone wrong' i think is the phrase

 

[E4gas]

Ive had similar on a heat only where the flo and return cant be to close in tempretureis resistance in the system opening the bypass?

How can I get out off this problem ,, micro bore not blocked , as rads getbhot

 

[kay-jay]

How can I get out off this problem ,, micro bore not blocked , as rads getbhot

If it locks out after a short time try draining g and refilling like i said before. I've had this two or three times on the 831.

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[E4gas]

I spoke to vaillant engineer , he said flow & return temp diff is only 5-7 degrees , instead off 15-20 ,, the rads heat up from cold , then the boiler is getting heat back to the return , to quick , boiler stops rads reheating as it's getting to hot , but the rads go cold ,, is there a link / bypass on micro bore manifolds ..

 

[AWheating]

sounds like the trv's are shutting down and the bypass is opening or bypass rad is keeping the room stat shut, take off the trv head and balance the heating especially the room with the room stat and see if the heating runs as the customer likes. If so get rid of the trv's as the customer probably wont get the head around how they work.

 

[E4gas]

Looks like I have to open up walls to find the bye pass near the manifold , and cut it out .. As the boiler has a built in one .. The lady wants the TRVs ,, but only kept on 3 ,,,she's not happy ,,