tankless heater plumbing

[Reds]

I have a Rinnai tankless heater on order. I am going to hook it up so that it circulates the resevoir water in my JCC self serve. I am only feeding 2 bays, and water for the soap & hp wax are all that get drawn out of that tank. I will be hooking up a circulator pump controlled by an line voltage aquastat, which is fed power from a timer. That way I can turn off the heater during the dead of night and it will only run when the aquastat calls for it. The only reasonable place I can mount the heater is about 15 feet from the SS resevoir and there are a lot of obstacles in the way (heater vents, plumbing lines, water service, etc). Has anyone ever used rubber hose (push lock?) for the feed lines to and from a tankless heater? Or must it be copper? The push lock hose is rated to 150?. PSI doesn't matter because it is an open system that simply circulates water thru the heater and resevoir. Hose would be a much simpler installation. Thanks in advance for any input

 

[MEP001]

Have you considered just plumbing it inline on the feed at city pressure?

 

[Reds]

I am worried that the flow control would restrict the volume of water entering the resevoir and not feed enough water to keep both pumps going at once. I also want to keep the water hot once it is in the tank so that the resevoir is always at the temp that I want. Do you think that if I plumbed it into the feed that the water in the resevoir would stay hot enough? I thought that by using it to heat just the water that's in the tank I could keep my water hotter. But then when I am busy I will have cold water dumping into the resevoir anyway. Maybe it's 6 of 1, half a dozen of the other? Have you plumbed them into the feed line and had it work? During the winter the state sprays salt brine on our roads every afternoon, and spreads salt all night. During that time of the year I have cars constantly lined up 3 deep to wash the salt off. Maybe it would be better to put it right in the feed line and insulate the tank real well.

 

[MEP001]

I'm not very familiar with the Rinnai, but I understand you can remove the restrictor and not have to worry about the flow. I was suggesting that in case it would simplify the install since you could put it anywhere on the feed line. As far as using hose, I don't see a problem as long as the temp ratings aren't exceeded, though you might think about something reinforced against collapsing. The hose from the vat to the pump on our Vector is just 1 1/4" reinforced PVC vacuum hose.

A friend and I talked about making a boiler that circulates water in the vat more efficient by using a PLC to kick the circ pump on as soon as someone drops in a coin. His thought was to have it come on right away and be heating the water while they're using tire cleaner/presoak, then shut off completely after everything's been idle for a while. I like the idea because if it rains all day you won't have a timer kicking on to heat water for no customers, but if someone comes in late at night they'll still get the same hot water everyone else does. Ours is direct feed from a pressurized, insulated tank, and even though I keep the tank level as low as I feel is safe, it takes about five minutes for the soap to get hot if the vat has cooled off.

 

[Reds]

MEP - thanks for the suggestions and help. When I get the Rannai I will look at it to see if the flow restrictor can be altered or removed. From reading the literature I am under the impression that it the cooler the water the more it restricts the flow. It will be interesting to see how it works. Thanks again.

 

[Randy]

There are couple of washes here that are set exactly like what you?re wanting to do. They all use Copper pipe instead of hose, the copper pipe will last longer than the hose will.

 

[Jeff_L]

How about PEX tubing? No sweating, just crimping.