[anarboran]

I plan to install a 1hp irrigation pump to water my lawn from a lake. The yard is about 15' above the lake and I need to run about 10 sprinkler heads. I think the pump will probably have more capacity than the 10 heads will require but I'm not quite sure. This pump will run on a timer while I am away (this is a part time residence). I will not have a tank or a pressure switch on the pump.

My concern is that if the sprinkler heads get clogged I may damage the pump if it can't get rid of all the water it is pulling in from the lake.

My main question is whether a pressure relief valve will solve this problem? (I've called the pump manufacturer but they weren't helpful.)

The suction hose is 2" and the discharge is 1.5" I would plan to install a "tee" fitting at the discharge, such that the sprinkler water would be delivered out one of the "tee" openings, and on the other opening I would install a pressure relief valve and from it a pipe heading back into the lake.

Would it work to have a pressure relief valve on a "side" discharge pipe instead of the main discharge pipe heading to the sprinkler heads?

And if it would work, what size of pressure relief valve would I need? The pump can deliver 42 gpm, but most of the relief valves I see look like they handle up to 25 gpm. Would that be good enough?

I'm a novice and don't understand plumbing particularly well but I'm trying to learn and would be grateful for any advice!

Thanks in advance.

[jlisenbe]

For twenty five bucks you could put a switch on it. If pressure rises too high, the switch will shut it down. Not the perfect answer, but worth thinking about.

Not too sure about a one horse pump handling 10 heads. Maybe, maybe not.

Having to pull from fifteen feet, I just don't think you are going to get 40 gpm. I would think that figure of 40 would be under very little pressure. Start pumping at 40#, and things change a lot.

[anarboran]

Thanks for the reply jlissenbe. A couple clarifications... the pump manual says the only way to use a pressure switch on this pump is with a pressure tank, which I just don't want to do. So I'm trying to find a way around that setup.

The manual also says the pump can deliver about 1800 gph at a 15' lift, so I'm hopeful that will be enough to run about 10 sprinkler heads. I can get by with only 6 if need be.

As for the 40gpm, that is based on no lift (or maybe 5' lift?). If it can only put out about 1800 gph at 15' then that would be about 30 gpm... that still leaves me wondering if a pressure relief valve that says it can do 25gpm is adequate?

I appreciate any further advice! Thanks.