Intellifaucet with Tankless Water Heater?

Hi there,

Does anybody use the 'low flow' Hass Intellifaucet D250 with a tankless electric water heater?

I've been told by a sales person that the Stiebel Eltron DHC-E8 tankless electric water heater will activate with a minimum water flow of 1100ml per minute and is adjustable from 86F to 125F, depending on inlet temperature. The Intellifaucet activates at a minimum water flow of 950ml per minute. It seems to me these two units would work together for darkroom use because the Intellifaucet's minimum volume for activation is well below the heaters.

I measured out 1200ml of 86F water (100 ml above the heaters activation volume to be safe) and added cold water from our local water system to bring it to 68F (as if I was washing prints), and it took 600ml. The way I figure it, this would give me a minimum print washing volume of 1800ml per minute.

Another factor which I don't know is applicable or not, is that the Intellifaucet has a minimum water pressure activation point of 10 psi.

I'm researching options for turning our garage into a darkroom. I'm pretty much sold on the Intellifaucet's "dial in the temperature you want and walk away" reliability. I've been advised in another thread to consider a 30 gallon hot water tank, and that's still on the table I guess, if I have to, but I'd rather go tankless if at all possible. I'll be using a 16x20 print washer that takes 22 gallons of water just to fill, and I hate running out of hot water...

Murray

That's some print washer you have there, 83.3 litres.

At one stage I ran the German Grohe mixer in my darkroom, feeding it from an instant electric water unit. This lasted for five years, until the instant hot water system imploded, shorted the switchboard and caused some other water related problems.

Eventually I installed an electric 45 litre hot water unit, under the darkroom sink. This has been a great success as the water pressure didn't change, but the delivery of heated water has come at nearly 45% less cost to heat.

Both systems worked perfectly with the Grohe mixer. I would assume the unit you have in mind, would work equally well, either way.

Mick.

I Mick,

Yup, the washers a beast. The Versalab 16x20 is on sale now for $295.00 U.S. so it's tempting...but big.

You tell a cautionary tale...if I do go tankless, it's going into some sort of cabinet so it can't spew water all over the darkroom if it blows.

Just to get this right; you are now using a 12 gallon (US) electric water heater and don't run out of hot water? You say you realized a 45% savings over the tankless heater...was this in comparing the purchase prices, or the cost of running the units over time?

I just measured the temperature of our cold water coming into the house, and it's 42F (3C) so that's another another factor to consider. It warms up a little in summer but not much, as our river runs on snow and glacier melt until the fall monsoons start.

Murray

I've been using the Intellifaucet at home. I can adjust it to 68 with 45F cold water coming in and a very low flow rate and it works very well. I use low flow washer, Summitek. They own the patent on all the cascading washers. They are great.

I have run out of hot water when my wife does the wash, runs the dishwasher, and I need to wash prints.

Other than that, it works great.

Murray, I just went into the darkroom to do some checking. Firstly my darkroom is a free standing 9'x18' building in the backyard, internal measurements. So I had to get everything there, water, power, etcetera. It wasn't as easy as just adding and re-routing plumbing through the house.

Originally I installed a Bosch electric (240V) instant hot water unit. Australia is 240V throughout, by the way. The apparent failure of the unit was more than likely due, to the electrician installing the absolute minimum sized cabling to run the unit. Over time the heat generated by sometimes longish running times, caused the cable at or near entry of the unit, to corrode and make brittle, the safety covering of the live wires. This took about 5 years to happen. It was only a matter of time before it was destined to fail. My In-Laws in Germany, have a near identical Bosch unit in their bathroom, it is over 25 years old and still going strong. I assume the failure was really down to the electical contractor under estimating the real possibility of heat corrosion on the cabling.

My current unit, is a nominal 45 litre unit. It actually holds 32 litres of water, which is 8.45 US Gal. This unit has an enamel lined water container, instead of the more normal and cheaper glass lined container. This reduces the internal capacity by a factor, so the smaller actual capacity reflects this. I had forgotten about that, until I just went in and had a look. Enamel liners are guaranteed for 10 years, as opposed to 5 years for the glass lined units. The cost difference was 4.5% according to the wife's calculations, so we went with enamel.

This unit is capable of giving out a reasonably continuous flow of heated water. The unit's thermostat is set at 51C, so that is the maximum you get. Obviously mixing will allow a reasonable output, but it can run coolish if you push it. I know this as we have a sauna in the backyard and run an outside shower off this same unit. When we have four people in the sauna and we have showers, it handles it. Make that six people and the unit is starting to struggle, but within reason it copes. Within about 5 minutes, it is back up to speed.

I had an interesting time with the Grohe mixer. That mixer was a mechanical one that had been retired from one of the labs at work. I duly fitted it to the darkroom sink, pleased as punch. I fitted it in Winter, when the water comes in at approximately 7-8C at it's coldest. It worked like a dream.

However the summer temperature is another thing. The mechanical system had a problem when I selected 20C for B&W work, when the incoming temperature was above 20C. The water flowed to a trickle until 22C was reached when it shut the flow right off.

This required some lateral thinking, I immediately placed some ice cubes in a plastic ziplock bag and wrapped this around the Grohe unit, water flowed again.

Well to cut a long story short, I retired the Grohe and currently it sits in the garage, where it's temperature dial tells me just how hot or cold it gets, expensive thermometer, eh!

Cold water currently coming into my darkroom, as of about ten minutes ago, was 26.5C. I assume that the new electronic water mixers allow for water to flow if you set them at 20C and the incoming water is above that mark. This could be something which is up to individual manufacturers specifications, I don't know, but it was something I didn't even think of when I installed the Grohe unit.

The running costs of the units were calculated two ways. Firstly, diminishing value which is the way a business would do it. As I run a business from home and used a darkroom for business purposes making litho negatives, this was good for that. Secondly, we made actual running cost calculations, which reflect day to day costs. As my wife is an accountant, she made sure everything that could cost money, was accounted for, trust me!

The bottom line according to her calculations, which were made almost 12 years ago, was an actual reduction forecast of 38% in electrical usage. After 5 years, actual costs were established at 44.7% under the actual running cost, of the instant unit that was previously installed.

My enamel unit was installed in March 1993, so the 10 year guarantee wasn't required to be activated. Hopefully it'll last quite a few more years.

Mick.

Hi Robert - that's good news about the Intellifaucet being able to run at "a very low flow rate" when the cold water supply is that cold, and thanks for the Summitek tip.

Mick - you have an incredible range of water temperatures to deal with there! Thanks for digging up the numbers your wife/accountant crunched comparing instant and water tank hot water supplies. Her 'real world' numbers differ greatly from the marketing hype that's on the tankless water heater websites, but that's not so surprising, is it?

Gotta go...daughter just thundered in

Murray

I have a gas fired Bosch tankless unit. First off temp control valves that use sense water pressure to control the temperature (i.e. typical compensted shower fixtures) play havic with the water heater, because the water heater reduces or increases water flow to control the outlet temperature. So the valve and the water heater end up fighting each other.
The other problem is that if you set the water heater's temp low (I can do this via a remote control), AND you set the valve for a low temp, you can end up with insufficient flow to activate the heater.
The other problem I get with my heater is that since there is no tank to catch the normal scale that forms it ends up in the water stream, so you'll want to make sure you have some kind of screen or filter for the water coming from your darkroom faucet.
If the Intellifaucet controls by sensing water temperature, then it should get along nicely with your tankless water heater. The other caveat is that if you are on a well, you might want to consider a pressure regulator so that you have a constant water pressure going to the heater. Otherwise when the pump comes on, it will increase the pressure and the water heater then must back off on it's output flow to compensate.
I don't have experence with any other whole house tankless heaters, but based on my experience with the Bosch so far, it seems like it doesn't deal with these changing conditions very well. Your unit may do a better job at it.
That is, sometimes if there is a large demand increase or decrease then it shuts off entirely for a second or two, and you end up with a slug of cold water coming through. It also doesn't do a very good job at maintaining the set temperature, but I'm not sure how much that is due to the other factors I've outlined here (I don't have a pressure regulator on my well, for example, at least not yet).

Hope this helps.
Barry