Trying to size Tankless heater...Help!
- Thread starter dogwasher
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robtl
central Ky
bigleo48
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What part of the counrty are you in and we also need to know what model of tankless you are going to use. Some are as low as 50k BTUs and others as much as 200K BTUs.
I would have an experienced HVAC guy look at your total consumption (in BTU) and some up with a number...then you'll know how many of what model you'll need.
I would have an experienced HVAC guy look at your total consumption (in BTU) and some up with a number...then you'll know how many of what model you'll need.
Hot water is for Automatics Pre soak tank, SS wax tank, SS pre soak, & SS hot water rise. The water here in Chicago I believe is about 45-50 degrees.
I have two Rennia Tanks rated at 180,000 BTU each, about 5 GPM with the factor of a 70 degree temperature rise that would get me to the 115 to 120 degrees that I want. I think these two tanks will do it but Im thinking they may be border line?
Actually I have been doing HVAC for the past 25 years but I dont know the GPMs my wash is using.
I have two Rennia Tanks rated at 180,000 BTU each, about 5 GPM with the factor of a 70 degree temperature rise that would get me to the 115 to 120 degrees that I want. I think these two tanks will do it but Im thinking they may be border line?
Actually I have been doing HVAC for the past 25 years but I dont know the GPMs my wash is using.
robtl
central Ky
Dogwasher, the Rinnai heaters have a flow control valve in them that will slow down the flow with increase of the differential between the income temp and the hot out temp.
I have installed these without a storage tank and had to go back and add storage because of low volume when trying to heat cold winter water to 120 deg. the flow was restricted so much that my hydrominders and fill valves would not work right.
how I use them is to keep the city pressure and volume to the storage tank and add a small circulation pump to circulate from tank thru rinnais.
You can also figure your gpm by adding your tips on s/s wands,and add up the tips on the autos, allow for about 1/4 of your total hydrominders working at the same time, this should get you close.
I have installed these without a storage tank and had to go back and add storage because of low volume when trying to heat cold winter water to 120 deg. the flow was restricted so much that my hydrominders and fill valves would not work right.
how I use them is to keep the city pressure and volume to the storage tank and add a small circulation pump to circulate from tank thru rinnais.
You can also figure your gpm by adding your tips on s/s wands,and add up the tips on the autos, allow for about 1/4 of your total hydrominders working at the same time, this should get you close.
robtl
central Ky
Dogwasher, at one wash I owned we had three Rinnai heaters piped in parallel with two 99gal gas fired water heaters,, at this wash this setup heated water for three water wizards, using hot water rinse, chemical mixing, rail and gantry heat, and floor heat for three bays and entrance aprons and exit aprons. we used a heat exchanger for the glycol in the floor heat. It worked well
The summer you could turn off the 99gal water heaters and just use the rinnai and cut the temp back and save a lot of gas.... Just a thought for you if you think it will be right for you.
The summer you could turn off the 99gal water heaters and just use the rinnai and cut the temp back and save a lot of gas.... Just a thought for you if you think it will be right for you.
Robtl, I looked into my hot water holding tank and found there are 3 Hydros and one float valve. Hydro #1 feeds the presoak for two automatics, Hydro #2 feeds wax for the SS, Hydro #3 feeds clear coat to the automatics, and the Float valve is hot water storage for presoak application in the SS bays. Im ready to tear into installing the Tankless heaters in the next day or two any feedback would sure help!
robtl
central Ky
Dogwasher, The only things I can think of is to pipe the two heaters in parallel and make sure to leave tees and valves and enough space to add the third if needed later on.
Also you can get a controller to sequence the two or three heaters to keep one from running every time on low fire.
make sure to use the venting system recommended for the Rinnai heaters
luck to you,
Bob
Also you can get a controller to sequence the two or three heaters to keep one from running every time on low fire.
make sure to use the venting system recommended for the Rinnai heaters
luck to you,
Bob
Kirby
Member
Dogwasher,
I have put a number of these in over the past few years and have used the Noritz and Rinnai. The most important thing you can do is figure how much hot water you would use at one time throughout your wash if each bay had the highest usage cycle (of hot water) on at one time. Do this by figuring out which cycle uses the most hot water in your auto's and self serves respectivley. Then figure your usage in gpm through your tips at whatever pressure you are using. Then figure in your hydrominders or mixing valves as well.
After all of that you should have a gpm figure. Will two Rinnai in series cover the usage? (I have always used a 5-10% variance when setting them up just in case tips get worn, valves wear, etc)
Hope this helps. Oh, by the way remember to install the cleaning manifold on each. Sure saves a bucket of time later when you clean them.
I have put a number of these in over the past few years and have used the Noritz and Rinnai. The most important thing you can do is figure how much hot water you would use at one time throughout your wash if each bay had the highest usage cycle (of hot water) on at one time. Do this by figuring out which cycle uses the most hot water in your auto's and self serves respectivley. Then figure your usage in gpm through your tips at whatever pressure you are using. Then figure in your hydrominders or mixing valves as well.
After all of that you should have a gpm figure. Will two Rinnai in series cover the usage? (I have always used a 5-10% variance when setting them up just in case tips get worn, valves wear, etc)
Hope this helps. Oh, by the way remember to install the cleaning manifold on each. Sure saves a bucket of time later when you clean them.
