Tempered Water - Low Flow Faucets

[ChrisConley]

We've been having problems on projects with point of use tempering valves matched with single temp infrared (or mechanically metered) faucets.

With all the LEED and conservation push we've been specifiying 0.5gpm aerators on these devices. The isse is that the amount of time that the faucet is running isn't sufficient to bring warm water to the fixture.

Anyone doing anything special with these installations? I've been thinking about chasing the hot water recirc down to the valve. Any other thoughts/solutions?

 

[PEDARRIN2]

We specify that the mixing valve be less than 5 feet from a recirculated main.

We also minimize the outlet tube to 3/8" OD to minimize the amount of water between the mixing valve and the fixture faucet.

We are required to use the 0.5 gpm aerators on faucets by the IPC. Although there is the little used caveat of using a metered faucet that flows more but has a shorter duration. It allows for more than 0.5 gpm at the faucet. It is an interesting twist which you might be able to use. Only a few manufactureres have it. Toto is one.

Good luck.

 

[mikanical]

Chris,

we've been dealing with the same issues up here (in Canada). We've been running the hot water recirc line (or heat trace) down in the wall to the fixture.

There are a couple of other options:

1. use an instantaneous water heater mounted near the bank of Lav's. Personally I don't like this option since you'd need about 4kW per Lav. The sparky would be ticked.

2. You could try and convince the AHJ to let you used 'engineered' pipe sizing to reduce the size of distribution piping. This, in conjunction with running the recirc down the wall, would help decrease wait times at the faucet.

 

[PEDARRIN2]

It used to be common design practice that you could be 100 feet from line to fixture. That was a long time to wait for hot water.

Then they told you to limit it to 20 feet. With the low flow fixtures, that is still a long time.

I have seen the heat trace used.

I also do not like instantaneous heaters unless I only have a single lav.

I once tried to put an instantaneous heater by a emergency shower which was rated for 20 gpm. My electrical counterpart would have had to bring a separate service intot he building just for this. I quickly changed the design approach.