RPZ vs check valve

[mbartosik]

Since my well pump was unfortunately a little oversized (3/4HP when 1/2HP would have done), I am going to use it to drive irrigation also.

The well is currently only used for ground source heat pump NOT drinking/house water.

Should I use an RPZ valve ($180) to separate heat pump from irrigation or will a simple brass check valve be sufficient (my guess $30) ?

[speedbump]

I don't know what an RPZ valve is, and I'm not sure I understand the question. Why would you need a valve at all?

bob...

[mbartosik]

I need to stop back flow of potentially dirty water from the irrigation system into the heat pump system. So I should use at least a check valve.

If you connect an irrigation system to a domestic water supply a check valve is not enough. In the United Kingdom they used to require an intermediate tank. In the USA an RPZ (reduced pressure zone valve) is required. It contains I think two check valves with a center chamber (zone) that can relieve pressure in case of failure of one check valve.

Currently there is an RPZ valve between the irrigation and domestic water supply. But my well supply would be tied into the irrigation side. I am wondering if a second RPZ to protect the geothermal system from irrigation is overkill or whether an normal check valve is enough.

Connecting the well to the domestic side is not good because the well is not tested for potatable water.

An example of an RPZ can be found here:
http://www.plumbingpages.com/feature...rviewGrant.cfm

[Rancher]

Probably a dual check valve assembly would be enough protection, that's all that's required on residential wells to city water supplies.

Rancher

[speedbump]

Here you can't connect water wells to city water in any fashion. It's frowned on heavily by the powers that be. In my opinion, the city would be contaminating the ground water not the other way around.
bob...

[sammyhydro11]

Speedbump,
its the same here in Massachusetts too.

SAM