Vaillant ecotech 831 - Not up to the job?

[sambotc]

Yep, close book on range rating, what you've said prove's it had F all to do with it as it isn't cycling.

Microbore is small diameter pipe 8 or 10mm usually.

 

[D_Hailsham]

There obviously isnt a TRV on the rad where the thermostat is located. schoolboy error isnt that one?

But there are plenty of installations which have TRVs on all rads and no TRVs (enough posts on this site on this subject), so I was just checking that your's wasn't one of them.

The CH output wasnt taken into account as i was told the boiler was more than capable of coping with size of house.

That's what they all say.

I called the gassafe engineer today and he told me he actually balanced system to try to address issue.

Makes you wonder if he knows how to do the job when there are TRVs on the rads.

The boiler doesnt seem to be cycling exactly as you say. It fires up to the temp displayed on the boiler, cuts out when it reaches that temperature then only comes back on when temp drops significantly.

But the boiler is cycling. When the set temperature is reached, it should be modulating down so that the heat produced is just enough to maintain the water at that flow temperature.

The Vaillant 831 modulates down to 8.7kW. A 3 bed house, 1 bathroom, 10 rads house may not even need that amount of heat, particularly if it is well insulated.

Check out the heating requirement using the links I gave earlier as well as the rad outputs. If you don't know your rad outputs, use the Stelrad Elite Catalogue. It will be close enough.

I turned on system whilst i went out and turned down all rads upstairs via the TRV's. When i came back the Rads downstairs are all getting much warmer (fully opened) but not with the intensity of upstairs rads. seems with prolonged usage it is getting better but the issue is still there. Im guessing as said many times earlier this points to a balancing problem.

Yup! And as I suggested earlier, the installer does not know how to balance systems with TRVs.

Lastly - Can i close book on rating the boiler? seems like it isnt required?

Not yet! There is a possibility that your boiler is unable to modulate low enough!

 

[mickyg]

Range rating helps the boiler perform better by capping its maximum on first fire but not doing it will not cause any problems.

You have hit the nail on the head; it's all about the first fire. The problem is that every time the boiler restarts it is treated as a first fire so, if the water gets heated up faster than the rads can dissipate the heat, the water temperature will rise to quickly and the boiler thermostat will kick in.

If you don't think this will cause any problems, there are plenty of cases on here where the problem was resolved by capping the maximum output of the boiler.

I'm not gonna waste my time explaining things to you but I have worked for Vaillant doing warranty repairs for 2 years and i know better than you so shh

Circulation/balancing problem period

 

[Razor900]

Well this is getting a bit tetchy isn't it?


I've seen more than a few installations where Vaillants haven't been range rated and if the difference between flow and return is too big they go to S.53.

DM himself posted a while back that they need rating to avoid this.

Not bothered to read the whole thread and it could well be a circulation issue but flaming D Hailsham seems a bit childish to say the least.

Most systems they work fine on right out the box but I've fitted them on all 15mm systems with 7 or 8 rads and they need rating to minimum output in order to work.

In any case as it would only take the OP 30 seconds to rate it down to 12kW or so what has he got to lose?

 

[mickyg]

Well this is getting a bit tetchy isn't it?


I've seen more than a few installations where Vaillants haven't been range rated and if the difference between flow and return is too big they go to S.53.

DM himself posted a while back that they need rating to avoid this.

Not bothered to read the whole thread and it could well be a circulation issue but flaming D Hailsham seems a bit childish to say the least.

Most systems they work fine on right out the box but I've fitted them on all 15mm systems with 7 or 8 rads and they need rating to minimum output in order to work.

In any case as it would only take the OP 30 seconds to rate it down to 12kW or so what has he got to lose?

we're talking about the 800 series combi which doesnt get the same S53 probs as the 400series, even so thats normally caused by poor circulation and bad system design and range rating just hides the real problem.

 

[Razor900]

From the guru himself


dangermouse46



Joined: 10 Aug 2008
Posts: 4326
Location: United Kingdom
Thanked: 112 times
Posted: Fri Jan 01, 2010 7:41 pm Post Subject:



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vaillant ecomax/ecotec fire up on 70% then go to value in d.0 before even looking at temp diff/flow temp and deciding to modulate.

P1 is the only way to get em running flat out; pressing "-" and "+" only puts it on d.0 gas rate.

btw if you fail to range rate the gw/vaillant range and there is a big gap between output and load you will get s.53 and poor performance/short cycling.
__________________
You get what you pay for. .


Now can we play nicely please

 

[mickyg]

All I can tell you is I've worked on over 1000 ecotecs and never seen S53 on a 60/800 series although I'm aware it can happen its highly unlikely. Additionally every time I've seen an S53 or F11 on an ultracom its been a system fault(poor pump, rubbish system etc). Range rating fixes the problem but doesn't FIX the problem if you get me

 

[Razor900]

I'm not saying that you're wrong 95% of the time it doesn't matter, just hate to see people that are trying to help picked on, (mostly not by you)!

Obvious answer is to turn off upstairs rads and see what happens, either way why would he have left it like that?

 

[Agile]

He already has turned down the upstairs TRVs and the downstairs rads surprisingly got better.

The simple answer is that it needs balancing and range rating.

The OP does not seem interested in doing anything apart from calling the installer who seems to have little experience. He has probably got paid and now has no further interest!

Only the owner can help himself.

Close all the lockshields with a spanner and then open each one just ONE whole turn downstairs and 2/3 turns upstairs.

Set the boiler maximum output power on d0 to 12 kW.

Tony

 

[sambotc]

No one has picked on anyone here.

The fact is a problem has been diagnosed which isn't even apparent. Even IF the boiler did need range rating which i'm convinced it isn't, the symptons the OP has described don't even relate to the range rating problem.

When the boiler come's up on temp the boiler will stop firing, but the pump will still circulate, so how does that stop radiators getting hot?

 

[sooey]

I've not read all of this thread, so has he been asked whether it's a microbore system, drop fed from a manifold.

 

[Deleted member 105431]

mickyg is right; range rating is for the 400's (s53), range rating the 800's is optional but I always do it (especially on high power combi's or oversized boilers). D Hailsham is wrong (all theory and no practical real world experience)

 

[Agile]

Sooey, he has has been asked if its microbore but just casually replied that he has no idea.

He has then been told how big a microbore tube is. Again he has not replied.

There is nothing to be gained by the professionals ( and D Hailsham ) arguing about it if the OP does not want to help himself.

Tony

 

[goon3r]

Close all the lockshields with a spanner and then open each one just ONE whole turn downstairs and 2/3 turns upstairs.

Set the boiler maximum output power on d0 to 12 kW.

Tony

Thx for this agile/Tony. At long last simple instructions an end user can follow!! I plan on trying this tonight. Will update all
With all the debating it was getting quite confusing.
Oh, and it does seem to be microbore pipework....10mm everywhere.

 

[sambotc]

I've not read all of this thread, so has he been asked whether it's a microbore system, drop fed from a manifold.

2nd page 2nd post down

Sounds like thats the problem, wonder if the powerflush has blocked the manifold.