Need help sizing a circulator pump for Tankless Heater/Storage Tank setup.

[GoBuckeyes]

I have a 600k+ BTU Raypack that needs to be retired thats paired with 115 Gal storage tank at one of our washes. The Raypack has had control/Ignition issues and has now sprung a leak and isn't worth putting any time or money into. I want to replace it with two Takagi T-H3-DV-N tankless units and need help sizing a recirculating pump to utilize the storage tank. At one of our other washes, we have this set up using two Huron Valley HE Heaters and a tank but that setup is using one pump per heater, and I was hoping to only need one. Does anyone have something similar that can offer advice? I was hoping that SupplyHouse.com would help sizing but they will not. A phone call to Takagi will be my next step when I have some time.

 

[Overachiever]

I built 2Biz's Takagi boiler floor heat system with two takagi t-h3s and 3x taco 0013s, two in series pushing it up into the tankless heaters and the other pushing out to the bays, seems like I get around 20gpm. I guess you wouldn't need that much if you don't need that much flow, but maybe that thread has insights.

Tankless Water Heater For Floor Heat

Warranty & future insurance thoughts Do you know if the warranty applies if you self install it? Some manufacturers won't warranty it if you install it yourself. Rudy & others, A lot of times the tankless does not have a local distributor or certified installer for their specific unit ... it...

www.carwashforum.com

 

[2Biz]

Takagi won't be of help either. I have the same demand heater for my floor heat. I Tried calling them for the same thing and their advice was way off. In order to get the 10gpm flow through that heater, you need 100psi. 40 psi gets you about 6.6gpm. Look at the flow chart in the instructions to get started. I have two taco 0013 pumps in series and I get 40psi to the heater. Good for 6.6gpm. When it comes to pump/pumps, choose wisely, 0013's are up to $450 now!

 

[GoBuckeyes]

2biz with your pumps in series, if you needed to isolate one of your heaters for whatever reason would that be too much psi or flow for the remaining heater?

Do the Takagi’s have an internal flow restrictor for when their output btu’s are ramped up? I’m assuming that’s why the decreased output for a higher output temp.

Thanks

 

[2Biz]

Not quite sure about the first question, I don't have two heaters in series. When it comes to pump physics, when you put pumps in series, pressure doubles, triples, etc but flow stays the same. When you put pumps in parallel, pressure stays the same but output volume increases.

The Takagi's do have internal flow restrictors. It will limit flow to maintain output temp. The flow charts in the manual are kinda hard to understand, but we'll worth the time it takes to digest what it means. Once you figure out what you want out of the heater/heaters it makes it easier to size the pumps to get the proper flow and psi.

You ever thought about getting an HTP tank style instead? It would eliminate the need for all the pumps and plumbing. I have the HTP 199-55 and it is awesome. I have a 4 bay. Best winter day the cw did 4400 gallons. Never once ran out of HW. I heat soap and wax.

 

[PaulLovesJamie]

I have the same setup as 2biz for floor heat - one takagi H3 with taco 0013s. But my wash water heater is different.

For heating wash water I use an HTP superstor storage tank, which has an indirect heating coil in it. I run a takagi T-H3 to heat the glycol in the heating coil, and I circulate it with one taco 0013.
This is enough for my rural 5 bay, but admittedly on extremely busy & cold days (teens/low 20s), it had trouble keeping up. Warm water yes, hot no. But thats only a few days over the last 6-8 years, I can live with that.
Based on the calcs I ran that caused me to use 2 tacos to push thru my floor heat takagi, I suspect to get the max # of btus you'd need 2 tacos for circulating to your storage tank too.
Time to run some calculations. Or you could just plumb it for 2 pumps, install only one of them, and if it doesnt keep up add the second pump.

 

[PaulLovesJamie]

btw, I agree that the HTP 199-55 is a good unit, that is probably the best/easiest solution if you're willing to discard the storage tank.

 

[Toms PTcarwash]

I have three Takagi 250 btu heaters piped to a 150 gallon storage tank in a primary / secondary configuration. One Taco bronze 0013 provides enough flow for all three heaters. The units I have will flow a max of 9.6 gpm and I believe need 1 gpm to trigger a start. Pressure is irrelevant.

 

[GoBuckeyes]

btw, I agree that the HTP 199-55 is a good unit, that is probably the best/easiest solution if you're willing to discard the storage tank.

I actually bought a HTP for another one of our locations about two years ago. It’s a very nice setup however, the prices for them have gone through the roof. Not to mention, about two months ago I had to buy another blower for the unit which was not cheap. I was pretty disappointed that I didn’t even get two years out of it.

 

[GoBuckeyes]

I have three Takagi 250 btu heaters piped to a 150 gallon storage tank in a primary / secondary configuration. One Taco bronze 0013 provides enough flow for all three heaters. The units I have will flow a max of 9.6 gpm and I believe need 1 gpm to trigger a start. Pressure is irrelevant.

Thanks Tom. Would you mind snapping a picture of your set up?