Pump installed wrong

[m0t]

We had a problem with a very noisy central heating pump for 6 months or so, and I decided to replace it (it seemed to me to be a bearing fault).

I replaced the pump this morning and the new one is much quieter but when I changed it over I noticed that the pipework is wrong. Because of the way the pipes have been laid the pump points slightly downwards, which according to the manual causes premature bearing failure.

In orded to get this straightened the pipes would need to be removed and relaid which I don't really want to do. Can anyone tell me how much of a problem this will be for the pump?

 

[D_Hailsham]

I replaced the pump this morning and the new one is much quieter but when I changed it over I noticed that the pipework is wrong. Because of the way the pipes have been laid the pump points slightly downwards, which according to the manual causes premature bearing failure.

In orded to get this straightened the pipes would need to be removed and relaid which I don't really want to do.

Is the pipe vertical? Which way is the water flowing? Why can't you rotate the pump until the shaft is horizontal? Post a pic if necessary.

Can anyone tell me how much of a problem this will be for the pump?

It will cause bearing failure, as you have found out. No idea how long this will take. Do you know when the old pump was installed?

 

[m0t]

Is the pipe vertical? Which way is the water flowing? Why can't you rotate the pump until the shaft is horizontal? Post a pic if necessary.

The pipe is vertical and the pump is pumping downwards. I can't rotate the pump because of its proximity to the wall - the casing hits the wall before it moves far enough to bring it to horizontal.

It will cause bearing failure, as you have found out. No idea how long this will take. Do you know when the old pump was installed?

No idea - the old pump was a Grundfos 15-60 and I replaced it with a new one of the same but the cases were different. On the old pump the cable clip had a different design and the switch was white, this is black on the new one. If any plumbers remember when this changed I'd be grateful.

 

[D_Hailsham]

The pipe is vertical and the pump is pumping downwards. I can't rotate the pump because of its proximity to the wall - the casing hits the wall before it moves far enough to bring it to horizontal.

So you have two problems:
Shaft not horizontal - result bearing wear
Pumping downwards - can cause cavitation

INSTALLATION
It is preferable to install Grundfos circulators in a vertical pipe pumping upwards. This position ensures that the pump shaft is horizontal, which reduces the thrust bearing load and ensures positive air purging from both the rotor chamber and impeller housing.

Pumping downwards in a vertical pipe is not recommended as this may lead to air locking of the pump, with resultant loss of performance. However, pumping downwards is acceptable provided an effective air vent is incorporated in the system, before the pump.

Where pumps can only be installed in horizontal pipework, it is imperative that the pump shaft is horizontal, or slightly higher at the vent plug end.
The shaft must not fall below the horizontal plane, even by a few degrees, as this causes premature wear of the top bearing and shaft.

Pumps should not be installed with the shaft in a vertical plane, as this may lead to dry running of the top bearing, noise and possible pump failure.

To avoid cavitation noise and risk of damage to the bearings the minimum pump inlet pressure should be 1.4m at 82°C (water temperature).

 

[m0t]

I saw that bit about pumping downwards being undesirable but there isn't a lot I can do without having all the pipework ripped out. It is just one of those situations where you wish it was done properly in the first place.

 

[Agile]

It is really NOT very difficult to correct that error.

The only important aspect is to have the impeller horizontal !

If the pipe is vertical then I dont understand how your motor shaft cannot be horizontal!

Tony

 

[m0t]

It is really NOT very difficult to correct that error.

The only important aspect is to have the impeller horizontal !

If the pipe is vertical then I dont understand how your motor shaft cannot be horizontal!

Tony

The pipe runs like this / out from a wall. At the point the pump is in the pipework is too close to the wall to turn it to make the shaft horizontal.