Rinnai

Jacob G.

I need to spec a heat source by tomorrow morn and am on the fence about making a decision.

I have designed a radiant system for a home in San Luis Obispo, CA (1600 heating degree days).1 zone is in the slab and requires
only 114 degree water. The other two are staple up and will require 131degrees.
The client wants to use a Rinnai instantaneous water heater for domestic.

Do I design a recirc and heat exchanger to use his system for the radiant.? Or buy a separate source only for the radiant? I need 54,000 BTU/hr at Max 5GPM. if I spec a separate source for the radiant I will have to justify an add'l water, gas and vent line.

What would be the most cost-effective choice for only 54,000BTU/hr?

Has any one used the litttle Raypacks? The little Takagi directly piped?

Kal Row

RANNAI is a better fit

than Takagi or raypak for a combo app - though i would like two of the smallest ones so that you dont have all you eggs in one basket, i'd go straight with hot water - and put them close to the water use point, and use a flat-plate-hx for heating - with a DMHW water flow switch to cut out the heating circ

ps if there are no teenage girls in the house, you can get away with one unit

also ranni gives you an outdoor mount version with built-in freeze protection if space is an issue - so you can hang it on the outside wall below the bathrooms - and run the pipe in and straight up to the bathrooms the shorter the run to the showers the better, a rule with tankless!

http://www.rinnai.us/ register on the site, and download all sorts of good info in the technical resources area

Alan(CaliforniaRadiant)Forbes

Alan(CaliforniaRadiant)Forbes

Hi Jacob:

Nice place...........San Luis........my son just got accepepted to Cal Poly and is deciding between there and UC Santa Cruz. Cal Poly was where Linus Pauling got his basic education; he's the guy that first did intensive study with viatmin C for better health.

We just finished a job in Berkeley that used a Rinnai for:

1) radiant slab downstairs and

2) Runtal radiators upstairs.

It is a commercial building; the husband builds and repairs harpsichords downstairs and the wife does aerosol engineering upstairs; DHW demands are very low, so we used a small electic water heater.

Choosing the heat source was driven by cost; the owners didn't want to spend a lot of money on the boiler and we installed a Rinnai because it was cheap. Cheap, but not efficient; mostly because you have to used a high head pump to overcome the pressure drop through the heat exchanger; that pump will be expensive to run.

If I was working on your job, I'd specify a Munchkin as the heat source (the T-80 sounds just right for you) with an indirect water heater. The Vision I system is an option when you buy a Munchkin (if you're a contractor) and it is specifically made for hydronic heating/indirect hot water/outdoor reset.

If your clients can't afford the indirect water heater, keep the Mucnkin and do something else with DHW (storage, Takagi, Rinnai, etc.)

Best wishes,

Alan

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Robert O'Connor_3

Get a combo unit

That's what they're made for. Baxi Luna has some built in controls already.
www.baxiluna.com
www.wallhungboilers.com