Danfoss BFP 41 L 3 Pump problems

[muckymick]

Hello all,

hopefully someone can advise, I have a Worcester Bosch heatslave 15/19 boiler, been running fine since last service. However two weeks ago the oil pump failed, engineer swapped and suggested likely water in the oil tank as it is an old steel one. so I ordered some water detection paste turns out there is no water in the oil. Anyway the new pump seized again after two weeks. I couldnt get the engineer out for a week so I got one online and fitted it myself. anyway it's still running! my question is, (finally) what can cause the pump to seize have been reading as much Danfoss literature as I can and nothing really stands out apart from water or debris in the oil, I have changed the inline filters in case there was crud in the oil, I am worried it may go again so have ordered another one just in case. Any advice would be much appreciated.

 

[Burnerman]

Water is indeed the oil pump killer......on this one there is a nylon filter below a round cover with one Allen screw to get to it.
Check the water trap bowl at your tank outlet for signs of water there.
John b

 

[muckymick]

Thanks for replying John,

There actually isnt a water trap on the outlet, now you have made me aware of them I will get one fitted, I just tested for water presence with Kolor Kut paste, which led me to believe there wasnt any water in the tank, at the outlet end and the gauge end which is lower. I took the filter out of the failed pump and poured the contents into a bowl and again no sign of water when tested and very little crud, although there was some and I am not sure how much tolerance there is in the pump for foreign bodies, very little I would have thought. I was hoping the kolor kut paste would change colour I had a water removal booked in case and although pricey it would have been a clear cause of the reason the pump died after two weeks.

 

[muckymick]

Sorry,

Can i ask does running the pump at a lower pressure cause problems, I am awaiting delivery of a pressure gauge, and as the pump comes at default pressure of 10bar I have turned it down albeit unknowingly how far down. I have marked the pump as best i could to the setting it was at prior to lowering so I could return it to factory setting if that is better until I get the gauge.

cheers

Michael

 

[Burnerman]

Hi Michael
Running the pump at a lower pressure wont harm things at all.....the 15/19 regular boiler runs at 100 psi, I believe.
The lower pressure will cause the burner to be unhappy though and may also produce smoke so I wouldn't adjust it!
When you say the pump is seized, was it actually locked solid?
John

 

[muckymick]

Hi John,

Thanks re the pump pressure, i'll push it back to default markings for now in case I have the pressure too low, and re-adjust when my pressure gauge arrives. Yes the pump had seized I stripped it down out of curiosity and when the pump casing was released it freed up, so maybe a foreign body in the gear wheel set? not much point to that exercise but I read a danfoss doc stating the gears could rust in a matter of hours if water had got into the system no sign of that so I think I will completely strip it down and take the gears out to see if there is anything obvious in there causing a pump failure, the damn thing ran without issue all summer!

 

[Burnerman]

Yes, its amazing how quickly rusting sets in - even more curious that kerosene doesn't stop it either!
Anyway, I'm surprised there isn't a filter come water trap after the tank valve, and it sure would be a bonus to have one.
John

 

[muckymick]

Thanks John,

old house nearly 150 years old so have had many battles on many fronts in the 9 months since moving in, CH being one of them. it was fitted 1999 so it's doing well, last service rated the boiler at 87% efficiency so definitly worth sticking with, heat slave tank is still good and rads piping when it works, Worcester Bosch wont cover it due to age. So i am having to get handy at fixing what I can! So a water trap filter will be the next thing done, thank you for your advice, priceless considering the wind and temperatures these last few days.

 

[Tipper]

Also be warned that in really, really cold weather any water in the water trap/filter can ice which will stop oil flow and cause burner lockout!

A little insulation wrap such ad an old blanket or jumper can stop this happening.

 

[Danoil]

Be aware that Danfoss are having localised problems with these pumps failing at the moment, we have sent several back this year and replaced three under warrantee this week alone. Danfoss have issued a press release regarding this at their findings so far so are trying to solve the issue.

Ps, don't leave your pump pressure at the default 10bar, you will have a locked out sooted up boiler before your ordered gauge ever arrives.

 

[Burnerman]

These older combi's are one of the best, Mick so stick with it!
It'll have a B9B burner, all the bits are available and it has no real weak points.
The diverters are a bit of an issue but easy enough to sort - the symptoms being heat to the rads but no hot water, and vice versa.
The baffles are easy enough to get at and clean - they come out through a hatch on the top....boiler cover off.
John

 

[Boilerman2]

Thanks for the heads up on BFP pumps - was unaware of this issue (not had issues ourselves as yet) but many thanks for very useful post!

 

[Burnerman]

Don't say......Danfoss are sourcing their pumps from China now.....
John

 

[Danoil]

I must say, our first thought was they are doing 'a Riello' on us, at least there are other manufacturers we can use if things do get bad, Delta etc, not like the Riellos where we were stuck with one make until they got their act together.

 

[Boilerman2]

I am very fond of Suntec Pumps - very seldom do I have to replace one of those (sadly they are not as common as they once were perhaps because they cost a little more)