Vaillant EcoTec Exclusive 838 13 rads

[Deleted member 105431]

I haven't read the whole two pages but I'd set d0 to 22kw, d1 to 8 and the pump to 100%. Balance the system with a diff thermometer and get as close to 15 deg temp difference. How clean is the system? Has a spirovent/magnaclean been fitted?

 

[Agile]

The Mouse has spoken..................

Welcome back Mouse!

 

[Doctorflip]

The rad sizes and room sizes are as follows. The house is detatched 1930s


Living room (5.18m x 5.18m x 2.59m) 175x52 double
Dining room (4.57 x 3.65 x 2.59m) 175x52 double
Kitchen (6.40 x 5.48 x 2.59m) 145 x 52 and 93x52 both doubles
Hall (3.65 x 3.65 x2.59m) 154 x52 double
WC 52x 52 single


Bathroom 2m x 3.5 m 83x52 double and 80x50 towel rail
Bedroom one (4.87 x 4.20 x 2.43m) 175x52 double
Bedroom two ( 4.60 x 3.96 x 2.43m) 154 x52 double
Bedroom three (3.07 x 2.48 x 2.43m) 114x52 double
Bedroom four (3.04 x 2.34 x 2.43m) 104x52 double


House has good loft insulation and new double glazing, no cavity wall insulation

 

[Doctorflip]

I have currently got the system on 30KW and bypass to max 350mb and pump on 100%, water overun at 5 mins and this seems to be not bad.
19KW as mentioned before was hopeless.
However it seems to still go onto overun quite a lot. For example I put it on this morning ro raise the temp from 17.5 to 18.5 it switched on then after a few mins went to overun with the readout showing 29 degrees - not sure what this relates to. The display said remaining off period 15 mins but it started again after only about 1 min. Then after a few mins switched off to overun. This was a different overun though. There seems to be 2 overuns shown on the display - the heating overun display and the remaining off period display. There is also 2 burner modes shown. It switches to the high one after a few mins on the low one.

So what are the views regarding the settings - is the 20 min anticycling time correct? I don't understand why it goes into overun so quickly.

Also why does the system not work well on the auto pump setting which is supposed to adapt to the heat demand.

Are there any other suggestions regarding optimum set up?

By the way the rads were all brand new in 2007 as was the boiler. the pipework is 3/4 apart from the last piece to the rad which is smaller.

The boiler is great for hot water and flow rate for a shower.

I'm currently trying to optomise the rad balance. I have thermostats on all rads.

Thanks very much for all your comments

Bob

 

[Doctorflip]

Could this be a balance problem causing the quick overun? I have tried a few different balance settings and it does not seem to make much difference. They all have thermostatic valves on and all the rads heat up ok though except one which seems to take a bit longer and the lockshield is max open on this one. I can get a thermometer and can try for a 15 degree difference as suggested by dangermouse

 

[Doctorflip]

the boiler control is via the Vaillant VRT360F

 

[D_Hailsham]

The house is detached 1930s

House has good loft insulation and new double glazing, no cavity wall insulation

You have about 22kW of rads which seems excessive.

What is the overall length and width of the house, measured internally?

Are the external walls cavity, but not insulated, or are they solid walls?

 

[Agile]

If the rads are 22 kW then thats the power setting for the boiler.

As you have discovered there are two different waiting modes.

I have a little concern about your balancing. You may well have too much flow through some rads.

I appreciate that you are reluctant to do the things we ask but you are more likely to sort it out if you do.

Balancing is done by the tool operated lockshield valve at the opposite end of the rad. If they have a hand knob thats wrong!

As a start I would suggest you close all those closest to the boiler and them open them JUST one turn, 3/4 turn on small ones. Ideally do this on them all but at least for a start do it on the floor near the boiler for example if all one zone.

The FAQ has instructions on balancing but what I am trying to achieve is a higher flow resistance.

Tony

 

[Doctorflip]

they are cavity walls not insulated - because I want to avoid condensation that a mate got in a similar house when he had cavity wall insultaion put in.

I don' t think I have too many rads, just one in each room and 2 in the kitchen and a towel rail in the bathroom. Also the boiler at 30KW should be presumably able to handle this output?

thanks

 

[Agile]

You seem to be taking a long time to understand that if your rads are a total power output of 22 kW then thats the power required from the boiler.

Oversizing the boiler means its less efficient and inclined to enter one of the waiting modes.

Tony

 

[D_Hailsham]

they are cavity walls not insulated

[/quote]
And the internal dimensions of the house are?

Condensation is usually caused by insufficient ventilation.

 

[Doctorflip]

Tony

when I put it on 19 or 22 it took ages to get heat to the rads and the overun was coming on about the same and I could not get the temp to 21 degrees evben after 5 hours. On 30KW I can get to 21 degrees, in fact 30 seems better than 27. I have no explantion for it and i understand your point but in practice it does not seem to work. Also I seem to get poorer hot water performance at lower KW, which is great at 30KW

thanks

Bob

 

[mickyg]

answer this question please..

doctorflip. are the rads new or old? did you have this problem with the old boiler?

if the answer is "they are the old ones and it all worked fine" then my answer to your problem is....

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.

 

[gas4you]

I still think it is a problem with the boiler and once again have seen this before.

Vaillant even refused to admit there was a fault. Boiler was removed 2 weeks later and I fitted a proper one that worked for the customer, strangley without changing anything on the system.

 

[Agile]

It might still be a boiler problem but until he has given some meaningful information on the operation we dont know.

I still wonder if there is too much flow through the nearby rads.

He needs to set it on heating and WHILE its firing to see what the flow and return temperatures are reading ( d40/d41 perhaps ).

Tony