Retro pump overrun

[joni os]

Want to arrange pump overrun. Current system, pump and boiler controlled by timer, when boiler cuts out on control stat. pump continues to run, no problem. When boiler and pump stop together on timer, residual heat is not dissipated and high limit stat. is thrown requiring manual reset. It is possible to lower temp on control stat. but this reduces DHW. temp, close to legionella territory.
A pipe stat. linked to energise pump when flow exceeds 75C would be ideal, except that as pump and boiler share a common terminal through the timer the boiler would also stay on.
Short of diodes, capacitors and purpose built PCB is there a solution.

 

[drip-dry]

so you just use a relay through a set temp stat maybe
one side of relay is linked to boiler and pump,the other to pump only

 

[BLOD]

What boiler is it ?: - does it require a pump overun, if not then probably best to cure the fault and not try to work around it.

 

[chris watkins]

As above
but if you do need to do this it should be possible so long as the high limit pipe stat is a single pole double throw as View attachment pump wiring .pdf

 

[joni os]

Thanks for responses. Boiler is commercial 100kw,oil,wired in parallel with pumps. Three terminal relay to isolate boiler when energised from temp. stat. would work. 240volt 5 amp switching. Any information on make and model of suitable relay much appreciated.

 

[albatross]

Heatmiser UK - Contact Details |

Try ringing heatmiser. They used to be good at making anything you wanted. I had a few relay boxes off them designed to my specification.

 

[Worcester]

Thanks for responses. Boiler is commercial 100kw,oil,wired in parallel with pumps. Three terminal relay to isolate boiler when energised from temp. stat. would work. 240volt 5 amp switching. Any information on make and model of suitable relay much appreciated.

Get a good sparks in - bread and butter stuff to us (think motor control) go to a good independent Electrical Wholesaler , they'll give you the right spec product, all the mainstream companies make then, lewden, chint, Schneider, hager ...

 

[Boilerbud]

Pump over run kit from Baxi part number 240340. Over run for about 3 minutes perfect for domestic heating Systems not sure if will work on industrial pumps, 5A is quite high. Four wires L, N, swl and Output to pump