Converted solid fuel range and central heating pump

knipex

I got a call from a mate last night to have a look at his immersion (Im a qualified electrician but have been out of the trade for a good few years)

It was an easy fix but while I was there he told me about a problem with his oil heating.

Its an old solid fuel range that was converted to oil (he plans on replacing it but cash is tight).

The issue is the pump. The range is on a timer and starts and stops fine. The issue is that so is his pump so it cuts out when the range stops so the water bangs and clatter lien mad in teh pipes and range. There was a stat fitted but it was shorted out.

I was going to send a permanent supply (through a switched spur) to the pump through a stat but the closest I can get a stat to the range is about 6 feet. My fear is that with a stat so far away the pipe will not heat enough to start the pump.

The other option is to still power the pump from the heating timer but fit a delay off timer to keep it running or an hour after the range shuts down (still with a stat so that if the temperature drops sooner it will turn off sooner) it will work but if its not needed then I don't really want to fit it.

The second issue is the way the pump is fitted. Its pumping into the top of the range boiler pushing the water out the bottom. (which seems wrong to me). He admits that it used to pump the other way (pulling water out of the top of the range boiler and pumping it through the rads) but he changed it as he was told to always pump into the boiler never away from it.

He also said that before he changed it the pump was pumping water back up through the expansion pipe into the expansion tank in the attic (I checked it still is).

Should I put the pump back the way it was and why would it be pumping back up into the attic ?

Its a small 4 bed bungalow with 8 rads.

Micky Dolenz

An hour is too long a delay, 5 or 10 minutes would be loads.

Are you sure the pump is pumping into stove and not out? can you see the direction arrow clearly on back of pump?

knipex

Micky Dolenz wrote: »

An hour is too long a delay, 5 or 10 minutes would be loads.

Are you sure the pump is pumping into stove and not out? can you see the direction arrow clearly on back of pump?

I agree an hour is too long but I will be wiring it through a stat which will cut it out once the temperature drops to a low enough level. I don't want to set it too short because I have seen rads stay hot for ages after a boiler cut out.

I am 100% certain that its pumping into the boiler. You can see the arrow on the pump quite clearly, its mounted horizontally and the arrow is on the top of the pump, every easy to see.

johnjoe 123

the pump should be on the return(lower) pipe pumping into the boiler or the flow pumping away or sucking through if u like. your cold feed from the expansin tank is being sucked bye the pump and is pitching up through your expansion pipe so ur exp. tank is acting like a rad. swith the pump direction. the stat will still work 6f away. put it on the return pipe if the range can gravity itself to the coil in the clyinder as the return wont get hot until the water in the clyinder does. if not put it on the flow and set it a bit higher. that should do the trick.

sullzz

id turn the pump the back around the other way so its pumping out of the boiler , check the size of the pump it could be too large for the system , or you could try turning the speed down , another option is to open the balancing valve on the cylinder another bit , this should stop the pitching

knipex

The coil in the cylinder is actually higher then the range, the range boiler sits on the floor and the cylinder is a 300L triple coil unit so the coil sits pretty high up.

The house was plumed 30 odd years ago (with a number of changes since). There are 3/4" pipes coming from the range with the T off to the cylinder coil. There is a manual leaver valve fitted after the T to allow you to heat water without heating the rads.

From memory the cold feed from the expansion tank (1/2" copper) feeds the bottom pipe and the expansion pipe leads from the top one (actually from the top of the coil on the cylinder with 1/2" copper)

I will turn the pump around and take come pictures tonight.

sullzz

knipex wrote: »

The coil in the cylinder is actually higher then the range

it doesnt matter where the coil on the cylinder is the reason you would open the ballancing valve is to let the circulation through the coil a bit more so it does not pitch , the ballancing valve on the cylinder at the moment is more thak likely just open a crack , try opening it half way.

knipex

Had a look and there does not appear to be any valve on the cylinder.

Will take pictures tonight and post them up tomorrow or Monday.