odd problem on boiler startup ecoTec plus 428

[williams]

been using the boiler/CH for about a week now off an on, just flushing out any gremlins before the cold weather arrives. have an odd problem with the boiler on start up....when i switch the CH controls on the boiler fires up immediately, runs for about 5 minutes gets up about 50 deg then stops..then it sits there for about 40 minutes when it fires up again and works perfectly until its switched off. same routine every time, have made no changes to the system since last year and the boiler has been serviced earlier this month

 

[ScottishGasMan]

When it's working it's way uptown 50 initially, and then after 10 min or so after its stopped firing, push the "i" button and note down the code, s.05 s.08 etc etc periodically and report back.

When it sits for 40 min not working in that time do the radiators etc get cold again

 

[williams]

thanks for the reply scottishgasman...no the rads stay warm and the flame indicator on the front panel is showing..and the temp keeps very very slowly dropping on the display..

thanks for the advice will do that..

 

[ScottishGasMan]

I'll put money on an s.53 while its doing the very slowly cooling run, but will need you to confirm first

 

[williams]

scottishGman...spot on S.53 code now what?

 

[ScottishGasMan]

Ok, so the reason your getting the s.53 is that the boiler is not getting the minimum required amount of water flow rate through the main heat exchanger, so the temperature rise from the water entering the boiler to the water leaving the boiler is too high, S.53 is a low running mode when the boiler notices this, so it stays lit but only on its minimum rate.

Roughly how many radiators have you got on the system?
can you tell what size of pump is fitted to the system and what speed setting its on? ie 15-50/15-60 speed I,II,III etc.

 

[ScottishGasMan]

You can manualy rate the boilers power down to suit the flow rate to prevent this, but the above information will give us a better picture what it needs rated to and if there are potentially any other issues causing it.

 

[Dan Robinson]

Change your heating pump to something like this

and everything should start to operate much more smoothly .

 

[williams]

ScottishGman......12 rads
pump is a grundfoss type MULTIHEAD G 230v p/n 59506180 class H
setting is on 3
settings are
0.17 - 40 1
0.30 - 65 2
0.44 - 95 3

This was working fine last year, so do i have a duff pump?

 

[jackthom]

It could be the pump, or among other things it could be the boiler heat exchanger becoming clogged.
So I'd ask how old the boiler and pump are, do you know how clean the circulating water is and is there a magnaclean or similar filter fitted.

 

[williams]

jackthom.......pump and boiler were installed new in Oct 2013, had the entire system flushed and upgraded. Magnaclean in place and virtually no crud in it at all

 

[williams]

Dan_Robinson......what pump is that?

 

[ScottishGasMan]

28kw heat only boiler running 12 rads is where your issue lies. Probably massively oversized for your requirements.

On the boiler you can push the two higher buttons at the display to take you to the D.codes (look at boiler instructions) you want to change D.0 to say 15kw to start with. Then try your heating as usual tonight, will find it s little slower to reach the 50*c mark but it should continue to climb till it his set temperature without the 40 min cooling period.

 

[ScottishGasMan]

 

[jackthom]

Edit: ScottishgasMan beat me to it.