Question about expansion tank, PRV and BFP

[TCP]

Hey guys new to the forum and new to home ownership! Recently my hot water heater went and I installed a new one. Upon testing my system pressure I found it to be 80psi. I left a gauge overnight on my hose bib and found it spiked up to 90 at one point. I checked for a BFP and found one on the sprinkler line only (no sure if one is buried for the domestic water) . So being the first time having sprinklers I was told by the sprinkler company that came to blow my lines out last season that the setup was a bit odd. I have the street line to the meter to a tee, one to the house and another to the bfp then to the sprinklers, all this at the well by the street. Coming into the house I have a shut off valve only.

The two lines coming out the ground I believe is a feed and the other goes to the house.

This line goes to the sprinklers.

My question is should I install a PRV? If so where and at what pressure should it be set to? Also if the PRV goes in the house do I need a BFP since the street pressure is always higher? In what order should this all be installed at. Also as it sits now I dont have a closed domestic system right so no expansion tank needed? Also 80 psi to the sprinklers is high no?

 

[hj]

That is about the pressure that I set my PRVs.

 

[Sponsor]

 

[Jadnashua]

A PRV is not a substitute for a BFP.

Code wants the home's water pressure <=80psi, so you can set it where you want within that range, but the higher it is, the more wear and tear on seals, hoses, etc. You'll want to add an expansion tank, if you do not have one, otherwise, your pressure will spike when the WH is running after you finish using hot - that expanding water needs someplace to go.

 

[TCP]

so what is the order ? Shut off valve - tee with gauge - union bfp - prv - union - tee with gauge - pipe to home? Also does an expansion tank on an open system provide any kind of protection against the rapid closing and opening of say a washing machine or dishwasher? Or is it completely useless in an open system?

 

[Jadnashua]

While gauges may be nice, they aren't a requirement! Other than that, I think you have it.

In an open system, an ET does not appreciably help with water hammer. The best location for an arrester is as close to the offending valve as possible - it's the inertia, and the whole column of water is moving...it must be absorbed at the 'wall', so to speak, not along the way probably long before it.

 

[Gary Swart]

You do need a back flow preventer. It must be on the irrigation line. This prevents fouled irrigation water from contaminating the domestic side. BFP should be certified annually to be sure it is still sealing. If laws are being followed, this is enforced, sadly some places ignore the laws and don't bother with inspections. In my city, the city water department inspects new installations. Thereafter, we receive a reminder letter with names and phone numbers for all the certified inspectors in area. It is our responsibility to contact one of these to come to the home and check the BFP. The inspector will replace any leaking seals, and make sure the device is holding properly. He then give the homeowner a copy of the report and sends the original to the city. Failure on the homeowners part to get the inspection will result in the water service being shut off. They are serious about this. Cost will vary a little from inspector to inspector, mine guy charges $35. Occasional repair parts are extra, but they are cheap. My PRV and expansion tank are on the domestic side of the system and do no affect the irrigation side. Your system look a bit odd, but I can't tell if it is install properly or not.

 

[Flapper]

My question is should I install a PRV? If so where and at what pressure should it be set to? Also if the PRV goes in the house do I need a BFP since the street pressure is always higher? In what order should this all be installed at. Also as it sits now I dont have a closed domestic system right so no expansion tank needed? Also 80 psi to the sprinklers is high no?

Your pressure is right at the limit so you probably should install a PRV; just use whatever pressure the PRV is preset to, and increase it if it is too low.
80 PSI is fine for sprinkers; our irrigation systems bypass the PRV and use the 90 PSI. Irrigation systems can handle up to 150 PSI usually, except drip systems which should be after a filter + regulator. But the filter, regulator, solenoid valves, sprinklers, etc, are usually rated 150.

 

[Flapper]

so what is the order ? Shut off valve - tee with gauge - union bfp - prv - union - tee with gauge - pipe to home? Also does an expansion tank on an open system provide any kind of protection against the rapid closing and opening of say a washing machine or dishwasher? Or is it completely useless in an open system?

I think the PRV should be before the backflow device.

 

[Gary Swart]

If you put a PRV before the backflow, then you cut the pressure down on the irrigation side as well as the domestic. Maybe that's what you want, but usually higher pressure is not a concern with the irrigation, in fact it might well be desirable to have more pressure there.

 

[Flapper]

If you put a PRV before the backflow, then you cut the pressure down on the irrigation side as well as the domestic. Maybe that's what you want, but usually higher pressure is not a concern with the irrigation, in fact it might well be desirable to have more pressure there.

Wait what's the device for? Protect the house or the entire property?

 

[Jadnashua]

The BFP is to prevent any pollutants from the irrigation system from getting either into the home's potable water system, or back into the supply to the street. Those could include insecticides, fertilizer, sewage (got a dog?), etc.

 

[Flapper]

The BFP is to prevent any pollutants from the irrigation system from getting either into the home's potable water system, or back into the supply to the street. Those could include insecticides, fertilizer, sewage (got a dog?), etc.

But he already has a backflow preventer on his irrigation system

 

[Flapper]

Oh wait so he's not adding a backflow preventer, he's talking about the one he already has?
Well then put the PRV after it where it goes to the house of course.

But if you would have a backflow preventer for your house (not irrigation system) then I would put the PRV before it.

 

[SteveW]

A comment was made about irrigation systems being able to tolerate 150 PSI. Not true in my experience. I've seen sprinkler heads pop apart with high pressures. Also sprinkler head manufacturers report that high pressures cause misting instead of the normal spray patterns. So -- wouldn't suggest letting a sprinkler system see too high of a pressure. Not sure where to draw that line, but 150 PSI is too high.

 

[Flapper]

A comment was made about irrigation systems being able to tolerate 150 PSI. Not true in my experience. I've seen sprinkler heads pop apart with high pressures. Also sprinkler head manufacturers report that high pressures cause misting instead of the normal spray patterns. So -- wouldn't suggest letting a sprinkler system see too high of a pressure. Not sure where to draw that line, but 150 PSI is too high.

150 PSI is the maximum of most of the parts of an irrigation system (valves, regulators, filters, etc)
I don't know what the maximum of the sprinklers usually are.

 

[Jadnashua]

Residential plumbing codes call for the supply to be regulated to 80psi or less. Your WH is also tested to 150psi (well, actually higher), but you wouldn't want to run it at that pressure, either. They test things for more than their designed operating pressure to provide some margin for error.

Running a higher pressure also means higher velocity through the pipes, which can lead to cavitation, noises, and wear.

 

[TCP]

ok so from the street it branches off to the sprinklers which has a bfp on that line. Then a separate line goes to the house with no bfp. Both lines are getting 80 psi and over night the pressure seems to go to 90 according to my gauge I have on the hose bib. So the line going to house I would like to bump down the pressure. Do I need a bfp or just a prv will be good enough since the pressure will be lower than the pressure coming from the street? Thanks.

 

[Flapper]

ok so from the street it branches off to the sprinklers which has a bfp on that line. Then a separate line goes to the house with no bfp. Both lines are getting 80 psi and over night the pressure seems to go to 90 according to my gauge I have on the hose bib. So the line going to house I would like to bump down the pressure. Do I need a bfp or just a prv will be good enough since the pressure will be lower than the pressure coming from the street? Thanks.

You don't need to put one if it's not required and since there's no one there, it's probably not required, so you don't need to put one there.
Just put a PRV there.

 

[TCP]

You don't need to put one if it's not required and since there's no one there, it's probably not required, so you don't need to put one there.
Just put a PRV there.

So I forgot to mention that when the sprinklers are going off the pressure drops to like 55 60. If the prv to the house is set higher than that let's say would it backflow? I did read somewhere that if the prv senses a difference of 10psi higher than set pressure on the house end it will backflow as a safety. But don't know if this applies here if it doesn't meet set pressure due to pressure drop from the sprinklers.

 

[Flapper]

So I forgot to mention that when the sprinklers are going off the pressure drops to like 55 60. If the prv to the house is set higher than that let's say would it backflow? I did read somewhere that if the prv senses a difference of 10psi higher than set pressure on the house end it will backflow as a safety. But don't know if this applies here if it doesn't meet set pressure due to pressure drop from the sprinklers.

PRVs will function like a check valve and won't allow backflow, which is why you hear about having to install an expansion tank if you install a PRV. Some PRVs have a bypass feature that will allow backflow.