No hot water when pro-installed irrigation system is running

Discussion in 'Irrigation / Sprinkler Forum' started by B.L. Jones, Jul 27, 2013.

  1. B.L. Jones

    B.L. Jones New Member

    Messages:
    2
    Location:
    Ontario
    We had a sprinkler system installed a few months ago and since the install, every time the sprinkler system comes on, we have no hot water.

    No water goes to our tank when the sprinkler is on. When my husband turns off the sprinkler system, he can hear the tank being filled.

    We have had the mixing valve replaced, turns out that was not the issue. A plumber came and looked at the tank and was able to get it working. It seems there was something stuck in the value that sits on top of the hot water tank, but he couldn't be sure. He (plumber) cleaned the valve out and the water came back. Keep in mind this may not have fixed the issue as the hot water would go off when the sprinkler system came on, and some random time later, we would have hot water again - some times it only took an hour or two after the sprinklers shut off, other times it took two or three days.

    My husband noticed the sprinkler system is installed before the water goes to the hot water tank. The water coming from the main it splits off 1/2" to the cold water taps in the house, and continues 3/4" to the hot water tank, but the sprinkler system is T-d off between the manifold (he thinks it's called a manifold but if not he can get a pic of it) and hot water tank.

    Our plumber thought he solved the problem almost a week ago, but tonight when the sprinklers came on, no hot water for us again :( Hubby turned off the sprinkler system and could hear the water going into our hot water tank, and instantly hot water came to our taps.

    Our pro who installed our sprinkler system has been installing for years and says he always installs the systems this way and has no idea why we are having issues.

    Does anyone here know what the problem most likely is?
  2. Murphy625

    Murphy625 Member

    Messages:
    155
    Location:
    Michigan
    I take it you're on a well system and not city water?
    Is your sprinkler system powered by the well water pump or is there a booster pump on the sprinkler system?

    Is your sprinkler system "down hill" from the home?

    It sounds to me like something in your sprinkler system is causing a pressure drop so severe that its almost, or is, a vacuum at your hot water tank. This could happen if you had an over-sized sprinkler pump drawing too much water from the home supply, or if you had sprinkler outlets located horizontally well below the home.. (think house on a big hill).

    Another issue could just be that your well pump is not even close to big enough to power both the home system and the sprinklers and maybe there's less pressure drop through the sprinklers than the home plumbing system and so that's where the water goes.

    One other thought... If you have a water filter installed for the home, it could be plugged and since the sprinklers probably by-pass the filter, the large pressure drop in the home causes the lack of water and it goes to the sprinklers.
  3. B.L. Jones

    B.L. Jones New Member

    Messages:
    2
    Location:
    Ontario
    We are on city water, and a small, flat lot and no water filter in the house. So it sounds like an over sized sprinkler pump may be a possibility, I'll ask the installer tomorrow, we phoned him this afternoon and he is coming by tomorrow. I'm fairly sure there's no booster pump on the system as our lot is fairly small (100' x 120').

    My husband suggested the installer place the sprinkler system after the hot water supply rather than t'ing off to it, but hubby's not sure if that would help or not, and since the installer has never encountered this issues, he's not sure if it will either, nor does he know what could be causing it.

    I agree with you Murphy625, it does sound like a vacuum/pressure is happening somewhere - hopefully it can be solved because I'm too old to be having this many cold showers!
  4. Murphy625

    Murphy625 Member

    Messages:
    155
    Location:
    Michigan
    I'm a bit confused now..
    You say you're on city water and that there is a sprinkler pump but no booster pump?? (The sprinkler pump IS the booster pump).
    If you have a sprinkler pump, I am 99% sure that it has a restricted suction and is creating a low pressure condition within your homes plumbing system.
    You want the feed line going to the sprinkler pump to be connected directly to the main (largest) water line that is coming into your home from the city. You will also require a throttling valve be connected to the discharge of the sprinkler pump. Once that is done, turn on the sprinkler pump with the discharge throttle valve opened just a little (1/8 open maybe). Now turn on a hot water tap inside the home and let it run. Open the sprinkler throttle valve slowly and monitor the water coming out of the tap in the house. Continue opening the throttle valve until you've reached a minimum acceptable flow rate of hot water. You are now set at your maximum irrigation volume your home water supply line can handle.

    Alternatively, you could also reduce the number of sprinkler heads you have on each zone. This would be the same net affect as a throttling valve but is probably a lot more difficult to accomplish once a system has been installed.

    One final note: If your sprinkler pump intake (suction side) is being restricted to the point of creating a vacuum in the home, your pump has probably been experiencing a condition called cavitation. This will slowly destroy the pump. You may want to have the pump taken apart to inspect the impeller for pitting. This condition should not have happened with someone who knows what they are doing.

    Its simple hydraulics.

    Hope that helps,,
  5. LLigetfa

    LLigetfa DIYer, not in the trades

    Messages:
    4,185
    Location:
    NW Ontario, Canada
    You are experiencing a severe loss of pressure at the HWT inlet and sediment from the tank is getting stirred up, jamming the heat traps. You could ask the plumber to permanently remove the heat traps. That would get you hot water right away when the sprinkler stops running but it could still affect the water pressure while it is running.

    If your home has a pressure regulating valve, see what pressure it is set to and whether the sprinkler could tie in before it. If the supply is inadequate, you may have to split the sprinklers up into smaller zones.
  6. Murphy625

    Murphy625 Member

    Messages:
    155
    Location:
    Michigan
    Oh good point.. For some reason I was thinking the whole house lost water pressure...
  7. LLigetfa

    LLigetfa DIYer, not in the trades

    Messages:
    4,185
    Location:
    NW Ontario, Canada
    If the whole house lost all of the pressure the OP would not be taking cold showers. I'm sure the pressure was down on the cold side as well, but suspect the hot side was worse and further worsened by the heat traps.
  8. Murphy625

    Murphy625 Member

    Messages:
    155
    Location:
    Michigan
    Two things have me leaning the other direction..
    1. Its a city water system.. If it was well water, I'd be looking at the usual suspects like sediment, scale, etc.. But not from a city water system... at least not from any city water system I've seen.

    2. The OP specifically stated that the sprinkler pump is drawing from the same leg that is feeding the cold water inlet of the water heater. I got the impression from the wording of that statement that the water goes through a manifold then to the water heater and some where in between, there is a tee that the sprinkler pump is connected to. This leads me to two different thoughts..
    a) The sprinkler pump is creating enough suction to draw ALL of the water and starve the hot water tank on that particular leg of the system. (leaving the cold water with enough pressure since it's being delivered by a different leg)
    b) The sprinkler pump is drawing so much suction that it is actually removing water from the hot water tank and thus causing an air pocket in the water tank when it sucks air in from an open tap in the home. When the 30 or 40 gallon hot water tank is only 1/2 full, the OP goes to get hot water, opens the valve and nothing comes out because the tank is still filling with water from being sucked down by the sprinkler.. (although this would probably manifest itself as air pressure blowing out the taps which should have alarmed the OP).

    If you are correct, its just a simple issue to fix.

    If I am correct, the sprinkler install person is an idiot and should have known better. I have to say, since my faith in the intelligence level of other people is at an all time low, (and getting lower as I grow older), I'm betting I am correct as I assume the sprinkler installer has little understanding of simple hydraulics.
  9. Wet_Boots

    Wet_Boots Sprinkler Guy

    Messages:
    798
    Location:
    Metro NYC
    I don't think you need a pump to see this sort of thing happening. Ever since pressure tanks on water heaters became common, the possibility exists of temporary reverse flow from house plumbing to a sprinkler system tied in at some upstream point.
  10. LLigetfa

    LLigetfa DIYer, not in the trades

    Messages:
    4,185
    Location:
    NW Ontario, Canada
    Actually there is no mention of a pump in the OP.
  11. Wet_Boots

    Wet_Boots Sprinkler Guy

    Messages:
    798
    Location:
    Metro NYC
    I wonder if the expansion tank is on the hot-water side of the heater. A drop in house water pressure when a sprinkler zone opens could make for a strong reverse-flow surge through the water heater.
  12. Murphy625

    Murphy625 Member

    Messages:
    155
    Location:
    Michigan
    Look at the OP's 2nd post in this thread.. he mentions city water and an over-sized sprinkler pump.
  13. LLigetfa

    LLigetfa DIYer, not in the trades

    Messages:
    4,185
    Location:
    NW Ontario, Canada
    You are baiting the OP with leading questions. It is not a known fact at this point, merely conjecture on your part. The OP doesn't know what she has.
  14. Murphy625

    Murphy625 Member

    Messages:
    155
    Location:
    Michigan
    Oh you might very well be correct...
    How did you surmise the OP is female?? Did I miss something?
  15. LLigetfa

    LLigetfa DIYer, not in the trades

    Messages:
    4,185
    Location:
    NW Ontario, Canada
    Not conclusive in this day and age...

  16. Murphy625

    Murphy625 Member

    Messages:
    155
    Location:
    Michigan
    LOL.. I totally missed that...
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