Vaillant EcoTec Exclusive 838 13 rads

[Doctorflip]

Many thanks to all who replied to my previous post on wed 4th Nov, much appreciated. I have a couple of other questions that I would appreciate comments on.

It was mentioned from my last message that with 13 rads I should put the partial heat load to 19kw

However even on the default of 27KW when I have the pump on auto and bypass at default of 250mb it takes ages to get the rads hot and the system struggles to get the house to 21 degrees even after being on for 5 hours. Even with the bypass at 350mb it does not make much difference. If I put the pump at 100% it can heat the house to 21 degrees just. However, on auto the heating seems to keep cutting off to over run so never seems to be on long enough to get to the target 21 degree room temperature.

My main question - Why cannot the auto pump setting which should be automatically adjusting to the system, failing to achieve a 21 degree room temperature. Is the partial load max value relevant here?

Also - regarding the other settable installation parameters:

1. what should the settings be for the heating flow/return reg changeover, (d17) It is on flow at present
2. Pump mode (d18) currently on return (0) - options are non stop and winter
3. d26 currently on 2

One last thing - it was mentioned that I should change the d1 pump overun to 7-8 mins as 'vaillant HE do not like heat'! Is this efficient though, as when the heating is on and you turn a hot tap on even for a few seconds you have to wait the overun time before the heating starts again. Surely that cannot be efficient for the heating?

Many thanks

Bob

 

[gas4you]

You need 7 minutes to get the heat out of the HE. I thought there were two pump over runs, heating and hot water, as designated by the different status codes

Your problem could be a system design problem and/or pipe sizing.

Not the first I've heard of with an exclusive not heating the property properly though.

Don't like them myself

 

[Agile]

If we have advised you to set the power to 19 kW then thats what you should do!

It seems you have the common problem of the boiler being over powered and turning off as soon as it reaches temperature and then wasting much of the time in the anticycling ( over run ) mode.

Do as we have advised!

Why didn't you do that when as advised you to?

If you are a medical doctor then its like a patient not taking his doctor's advice and then wondering why he has not been cured!

Tony

 

[Doctorflip]

Tony

Thanks for the message. The reason that I have not changed it yet is because the previous response (not from you) just suggested an approximation KW based on the number of rads. The person replying did not ask about the rad size etc so the calculation might have been flawed. I have 13 double rads. Your explanation about the boiler perhaps being overpowered and shutting off was helpful so thanks for that, that makes sense.

I am a surgeon and I always like my patients to question my suggestions and never take offence at this.

Regards

Bob

 

[glasgowgas]

post back the lengths of your double panels in metres for an approximate Kw output

 

[mickyg]

This boiler should work absolutely fine at factory settings. It doesn't need any adjustment. If it doesn't work properly call your installer to investigate, as either the boiler is faulty or there's a problem with the system. I would strongly suggest resetting to factory settings.

 

[Doctorflip]

Rad sizes are

All sizes in cm

175 double
154 double
114 double
104 double
83 double
83 double
154 double
175 double
175 double
93 double
145 double
80 single
52 single

thanks

 

[Doctorflip]

I forgot to add that they are all 52cm high Myson double convectors on all but the 2 singles

 

[glasgowgas]

after a quick tally up, make that appox 30 kw +/- a Kw

 

[Agile]

I agree that the rad load should be adequate to leave the boiler set at 27 kW.

However, I am concerned that the autobypas is not set correctly.

Can you set it to 2000 mB ( or maximum if lower ) and that may solve the problem.

If set too low it recirculates flow water to the return without cooling.

I would say set the over run ( d1 ) to three minutes as that will reduce the problem which you currently have although correcting the bypass should solve that.

If it makes you feel good as a surgeon then even if boilers dont work or an installer makes a bodge trying to fix them the at least they dont die. ( often )

I did a repair for a chunky Nigerian lady surgeon who said there were few female orthopedic surgeons because the work was very physically demanding. Somewhere else I read they used some power tools from B&Q, power jigsaws etc. !

Tony



PS Does this model not have a built in bypass set by a brass screw to the left of the pump?

 

[gas4you]

Don't forget this is a Vaillant exclusive boiler. Expensive over rated carp and prone to faulting as op described

 

[doitall]

Don't forget this is a Vaillant exclusive boiler. Expensive over rated carp and prone to faulting as op described

And Noisy Dave

 

[kevplumb]

Don't forget this is a Vaillant exclusive boiler. Expensive over rated carp and prone to faulting as op described

thought you where all for vaillant dave

 

[Doctorflip]

I changed it to 19KW and it was hopeless - I've put it back to 30.

Tony - the bypass is a screw with adjustability from 170mb to 350, the default is 250 which is what it is on now.

Regarding the overun - some conflicting views here? The pump overun is currently on the default of 5mins with the anti cycle time on the default of 20 mins. The range for the anti cycle is between 1-60 minutes

I've got the rotary knob for the heating at 75 degrees

thanks

 

[Doctorflip]

Also, I've put the pump back to 100% as performance seems poor on the auto setting. I don't understand this as this is supposed to adjust automatically to the system. Any idea why this would be the case and should I try with the pump at a different % speed or will that stop it working at 100% when it needs to?