Pumpover.

[DP]

A while ago there was a post about pump over. It ran over several pages. I cannot remember if the discussion resulted in a solution to pump over problem. What is written below is a similar problem on a real system and it has been resolved. Following is to be an exercise for new entrants to the field of boiler repairs and those who carry out this kind of work everyday. This discussion can be debated in combustion chamber where this post is echoed as well. Finally, if you know the answer, email me if you like confirmation.

Boiler is an old Gloworm wall mounted boiler (the one that uses McLaren gas valve). Return has a Sentinel sediment filter unit fitted to it. Flow runs horizontally with first tee for 22mm vent and second tee (branch 15mm) to feed and expansion tank within specified 150mm distance between vent and feed pipes. The F&E pipe drops to double on itself to rise steadily to header tank. Flow then drops to the floor with pump fitted halfway on the vertical pipe. Pump is a Grunfoss 15/60. System is fully pumped S plan

Boiler is fitted in the garage and F&E cistern is in the loft space above the garage. House is single story bungalow. Vent rises above the header tank by some 400mm to drop down to the header tank. Vent outlet is above cistern water level.

New pump was fitted. Old pump bearings were shot. Pump over started when new pump fitted. Pump set to speed 1 setting

Would anyone like to guess what the problem was? I have to say above setup cannot result in pumpover if plumbing is correct. Plumbing at this house was correct.

No prizes.

 

[Gas2Air]

Bypass fitted?

 

[picasso]

new pump on upside down?

 

[gas4you]

Pump fitted the right way round? Cold feed blocked?

I've had this, but luckily the very few times it has occured an aerjec being fitted has cured it, although in theory it should make no difference.

 

[Aquaheat]

New pump fitted in wrong direction?

 

[DP]

No to above 4.

If the cold feed were blocked, pump over would not take place as feed would not allow water to flow.

It is a cast iron block. Rarely was a bypass fitted to these installations.

I fitted the pump. Was not having an off day so pump was fitted correctly.

 

[Agile]

As far as I can interpret that arrangement, then pump over could only arise if there was a blockage in the 150 mm between the vent and the cold feed connection.

However, I dont feel as confident as I should be as Danny may have concocted a blockage with a haggis or something.

Tony

 

[doitall]

A couple of things I would check, does the boiler have a spreader tube, and one other that I still need to consider.

 

[Gas2Air]

Dunno the answer, but if pump bearings were shot, tends to lead to area of pump, config. Why change?. A pump on speed 1 for 15/60, small bungalow? However i have a feeling it's not to do with the install, clue is boiler.

Ven(pumpover)t is there for temperature/pressure.

 

[doitall]

A low static head would give this problem, but Danny has said the system is installed ok.

 

[DP]

John, no spreader that I know of.

System was always noisy, as was the old pump. Some rads had cold patches. These rads were removed to flush out to remove blockage.

New pump set on 1 heated the house very well but also resulted in pump over; old pump did not.

 

[doitall]

Did you have to alter or replace any pipework.

 

[D_Hailsham]

Wrong pump? Should have been a 15/50?

 

[namsag]

All piped up ok and you never altered any pipework or different pump to repair.??
Electrical ?

 

[DP]

No pipework was replaced or altered.

After repair, pump was set to 3. No pump over.

Problem was not electrical.

Suggestion. Make a sketch and reason why pumpover would take place. That is what I did. Went straight to the problem area and fixed it.