2007 EPA WaterSense lavatory faucets and tankless heaters

ChrisDIY · 10-05-2010, 11:36 AM

Has anyone else out there found that they are having trouble keeping the tankless heater running with the new WaterSense faucets? The maximum flow rate is 1.5 gpm and my Rinnai needs a 0.6 gpm flow rate which is cutting it real close! I am working on increasing the total flow in the house so every faucet will run at the maximum flow rate. Right now when just the hot is open I can get 0.7 gpm but when cold is opened it drops to somewhere between 0.5 and 0.6 gpm and the unit stops heating. This occurs at a fixture at least 68 feet from heater with 3/4" pipe.

Any word of a retrofit from manufacturers that will lower the minimum flow as these units were designed using the 1997 standard??? Rinnai are you listening?

ChrisDIY · 10-07-2010, 02:02 PM

...that's a difference of about 1.28 oz. a second, not very much.

ChrisDIY · 08-02-2011, 11:10 AM

I contacted Rinnai and there is no plan to have a retro kit for the tankless units with crack of 0.6 gpm to be reduced to 0.4 gpm. So tankless have been given title of "the best thing since sliced bread" and have many benefits, but there is an Achilles heel.

Having to turn hot on all the way is "wasting water...?"

ChrisDIY · 08-25-2012, 11:02 AM

Rinnai should stop selling their hydronic air handler, the use of the thermostatic mixing valve and water sense faucets DOESN'T WORK!

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wassermeister · 08-25-2012, 05:11 PM

The old units are not that sensitive for sure - can you lower your hot water temperature on the tankless unit? If you were able to lower it you can use more hot water at the faucet thus creating the flow that you need to trigger it.

You can also change your aerators to a higher flow rate. WaterSense just means that you need a flow rate of less than 2.5GPM at the faucet & they need to be pressure compensating to ensure continuous flow. You can get models with 2.0GPM, 1.5GPM, 1.0GPM. The swap out is easy. If you want high quality aerators consider the Neoperl product. You can get them on Amazon or GP Conservation. It's engineered by the Germans and made in the USA. They cost next to nothing. It is the same stuff that goes in high end faucets. I have swapped the aerators out at my apartment complex. It is really easy. You can do this by hand.

In any case I would recommend trying to reduce the hot water temperature first. If this does not do it go aheead and swap the aerators out for something with slightly higher flow.

What is the use of a tankless gas water heater if you don't get hot water?

Javiles · 08-25-2012, 06:38 PM

we just change out the aerators,or pull the restricter, we have been running in to no hot water at fixtures from POU heaters, some have tamper prof aerators. why people have these tank less heaters installed is beyond me. gas ok electric garbage.

ChrisDIY · 08-25-2012, 11:51 PM

I have to check again, I thought when I called Kohler they said flow restriction was in cartridge, not aerator.

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ChrisDIY · 08-26-2012, 12:07 AM

Quote:

Originally Posted by wassermeister

The old units are not that sensitive for sure - can you lower your hot water temperature on the tankless unit? If you were able to lower it you can use more hot water at the faucet thus creating the flow that you need to trigger it.

You can also change your aerators to a higher flow rate. WaterSense just means that you need a flow rate of less than 2.5GPM at the faucet & they need to be pressure compensating to ensure continuous flow. You can get models with 2.0GPM, 1.5GPM, 1.0GPM. The swap out is easy. If you want high quality aerators consider the Neoperl product. You can get them on Amazon or GP Conservation. It's engineered by the Germans and made in the USA. They cost next to nothing. It is the same stuff that goes in high end faucets. I have swapped the aerators out at my apartment complex. It is really easy. You can do this by hand.

In any case I would recommend trying to reduce the hot water temperature first. If this does not do it go aheead and swap the aerators out for something with slightly higher flow.

What is the use of a tankless gas water heater if you don't get hot water?

thermostatic mixing valve requires minimum flow of 0.5 gpm to work, add Rinnai at 0.6 gpm. New version is 0.4gpm. Rinnai says no conversion kit will be available. Faucet is 1.5 gpm 0.75 gpm per cartridge. We are on a well so pressure and flow losses...

That is one thing I don't know, what well pressure tank setting will give highest flow rate. Currently 40/60

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wassermeister · 08-26-2012, 12:49 AM

If your fixture is WaterSense certified it should be pressure compensating. This means that should have a true 1.5GPM flow. Can you get a cartridge that will do 1.0GPM on the hot side?

jaydevries · 08-26-2012, 09:31 AM

try this simple solution for on demand recirculator pump
http://www.gothotwater.com/

ChrisDIY · 08-26-2012, 11:20 PM

Quote:

Originally Posted by jaydevries

try this simple solution for on demand recirculator pump
http://www.gothotwater.com/

I thought that was made by Taco? This would get hot water to faucet but would create a cold water sandwich since can't maintain high enough flow.

Thanks though

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ChrisDIY · 02-02-2013, 10:52 PM

Just upgraded the manifold in anticipation of the new master shower and to eliminate the water hammer problem we were having. Shower now works great no hammer whatsoever. Now none of the sink faucets can kick the tankless water heaters on. What a nightmare! Apparently tankless heaters as the flow increases the pressure drops, which caused water hammer in our shower. Fix was two thermostatic mixing valves. Looks like I'll be having them taken out! Downside is our back-up heat will have a low delta rise...

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ChrisDIY · 02-06-2013, 03:53 PM

The two valves have been taken out. The design of the Hydronic heat doesn't work well with a multi unit install with low flow and high flow requirements. No water hammer and all faucets now work fine. For the first time we actually have lukewarm water.

2007 EPA WaterSense lavatory faucets and tankless heaters-forumrunner_20130206_154731.jpg

Just too many incompatible components. First being the WaterSense faucets. Second tankless pressure drop to maintain water temp. Lastly, bath design involving multiple simultaneous water fixtures.

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