Pump in reverse?

[PaulAH]

A "qualified" engineer has fitted a replacement Grundfos pump (UPS 15-50) to our oil-fired system. I've just noticed the flow direction arrow is pointing upwards, when the old one pointed downwards. The pump seems to lie in the the cold return, so the old arrangement made sense. However, I note that Grundfos do not recommend pumping downwards because of the risk of air locks. Has he done the right thing by reversing it or is this asking for trouble?

 

[weargas]

the pipework coming from a boiler is only meant to circulate one way (flow is often at the top of the heat exchanger to remove water at it's hottest) so if it's pumping away from the return than you should have it turned round.
he's probably done what i used to do regularly when i was a nipper and take pumps off without noting the arrow direction, at least i had the moxy to trace the pipe and fit the new pump the correct way.
get in touch with the engineer and voice your concerns.

 

[PaulAH]

Thanks for that - you confirmed my suspicions. The boiler has also been behaving oddly since the pump was fitted, probably through overheating. I guess its internal themostat is positioned to sense the temperature of the hot outflow. If the flow is reversed, it will be reading the cooler inflow and over-cooking itself to try to bring itself up to temperature. Would this be correct?

 

[ChrisR]

That's about it. motorised valves tend to let-by as well.
I got a pump backwards once (to my knowledge!) & the guy lived with it being a bit odd for a month!

 

[Gees]

I did the same thing with my last gas boiler. Put the pump in the wrong way round. The boiler only lasted a few months after that but BOY was the central heating HOT. Thermostat on RETURN pipe......

 

[PaulAH]

Thanks, guys. You have given me enough ammo to shove this "engineer's" head up the flue. Sorry to hear about your troubles, Gees. At least you were warm for a month. I think my boiler is now for the graveyard, but it is almost 30 years old.