Circulating pump for hot water heating system

[joenicole]

Hi,

I have an Armstrong circulating pump model S 25-BF on my hot water heating system. The pump started leaking water just outside the pump housing.

I checked with a plumbing contracter and he suggested, because the pump is 10 years old, that I should replace the pump altogether. He suggested the following:

1- Armstrong pump, same model
2- Grundfus model 1542 of similar capacity

Is anybody familiar with the Grundfus pump? Is it really as good as the Armstrong? Apparently it is European made.

Can my Armstrong pump be repaired by just changing a gasket?

Your guidance will be appreciated. Thanks.

[sloooo]

Grundfos are good pumps. As far as replacing the gasket, with your pump being 10 years old, and since it is a smaller pump and cost won't be through the roof, if you can afford it, I would just replace the pump. But if cost might be an issue, you should be able to find a gasket online. If not, they make gasket material and you can always cut your own. If you do, make sure you use hi-temp RTV silicone one both sides of your gasket. This will assure that you will be drip free.

[joenicole]

Thank you sloooo. At the dealer's suggestion I purchased a more powerful
Grundfos UPS1558FC pump with 3 speeds. The only thing that bothers me is that the water in the heating system is not clean water. Even though I partially emptied the system, there is still (dirty water) there. This might clog or cause damage to the new pump since water gets into the motor and bearings. The old Armstrong had a 1 inch opening while the new Grundfos has a three quarter inch opening. In the Armstrong pump the water is isolated from the motor. Not the case with the Grundfos.

I have not yet installed the new pump but I will try and flush the system some more. Any further advice? Thanks

[sloooo]

Is this a closed loop hydronic system with a seperate water heater, or are you using your domestic heater that feeds hot water to the rest of the house?

[joenicole]

It is a closed loop hot water heating system to heat the house going through an oil fired furnace. Domestic hot water is a separate system entirely.

[sloooo]

Ahhh, got it. Does it have a holding tank or is it just the pipe with an expantion tank? One thing you can do is place a hose on the inlet side of the pump, and place another hose on the fitting that would be going into the inlet of the pump. Then take the second hose that will have the water coming from the system and run it outdoors. Then turn on your hose, then turn on your pump and let it run until you have clean water coming from the exit hose. This will assure you that you have no particles going into your pump since your running clean water into it and you will be able to see what is comming out of your system and know when the flush is complete. You can get hose adapters to hook up the hoses at any Home Depot or Lowe's.

[joenicole]

It has an expansion tank. I asked the dealer if I should flush the system with new clean water, and he felt that it is not necessary and that he never had complaints of pump failure because of the stale water (black) in the system.

In any case, at least half of the water in the system was replaced. I finally installed the pump and it operated like a charm. Thanks.

[sloooo]

Great to hear!!