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samglass · Jan 31, 2011, 08:53 AM

Our outside faucets use up all the hot water when they run for an extended period (like watering the gardens or filling the hot tub). We have two 40 gallon hot water tanks and all the hot water is gone when we use the outside faucets. We have had plumbers check to see if the hot water lines are crossed to the outside and they have told us they are not. What is causing this and how do we get it fixed? Thanks.

massplumber2008 · Jan 31, 2011, 10:24 AM

Hi Sam...

Any faucets close by? How about a single lever washing machine valve? Here, I would recommend isolating each faucet in the house by shutting the hot water shutoff under each sink and then test the outside faucets to see if the issue is resolved and to determine which faucet/valve is involved.

If no faucets are the issue, then it could be a SHOWER valve issue, but these don't usually have shutoffs associated with them so pop back after testing all the faucets and let me know what happened, OK?

Most likely one of the mixing valve cartridges has gone bad and needs to be replaced.

Mark

samglass · Jan 31, 2011, 01:28 PM

Mark: Thanks for the quick response. Well, the issue only occurs when large amounts of water are running through the outside faucet (like hundreds of gallons) for several hours of watering the gardens or filling the hot tub. Turning the outside faucet on and just letting it run for 5-10 minutes or more doesn't create the issue. Currently, the way the house is plummed is the main water line has been extended from the front main entry to the house to the back; a shut off valve was added; and a whole house water filter was spliced on the line; then all the water runs through the whole house filter including the outside faucets. When the outside water runs, it pulls all the water including that from the hot water tanks. One plummer is suggesting adding a T on the other side of the whole house filter and running new separate cold water lines to the outside faucets. The thinking is that when the outside faucets are turned on, the water will go directly to the outside faucets and there will be enough pressure to not pull any of the hot water. Does that make sense to you? Thanks. Sam

massplumber2008 · Jan 31, 2011, 05:41 PM

Hi Sam

I need to be careful as I am not on the job, of course, but I am having serious trouble swallowing the explanation presented.

I mean, I have hotels with 10 floors and huge water heating systems with tons of outside faucets that are used to water huge lawns, gardens, water areas, etc. and none of them pull water from the water heaters. I have huge homes with similar setups... no issues, you know?

Now, it's not that I don't think moving the water lines wouldn't help... it might... AND simply put, I think it makes sense to keep the outside faucets from going through your filter so I would start there, for sure. If the issue returns then I would still suspect a faucet or other valve in the home is allowing a cross connection to occur and it slowly pulls and finally creates a drag on the hot water system when great volumes of water are used. *shrugs*

In that case, I'd at least try isolating the issue to the faucets/valves as I mentioned in my last post the next time you go to use great volumes of water... Here, I'd just shut all the hot water shutoffs to every valve. If no issues during this test then the issue is at a faucet/valve and you would just need to isolate the particular valve to resolve this.

If you still had issues after that and it isn't a faucet/valve and some how the water heater is being siphoned off I would think that it may be a good idea to install a vacuum relief valve, a check valve or even a backflow preventer at the cold water inlet to each heater... should stop any kind of backflow condition dead in its tracks... ;)

Anyway, that's my thoughts. I'm sorry if I only add to the confusion! *UGH*

Care to discuss more... let me know?

Mark

samglass · Jan 31, 2011, 05:52 PM

Thank you. We'll proceed with the separate line and if that doesn't fix it, we'll investigate the valves as you suggest. The plummer we are using is fairly certain that the new line should fix the problem. I sure hope so. It's expensive in the summer to keep filling 2 hot water tanks. Thanks again. Sam