tankless hot water vs. hot water maker

jeff_95

we are doing a home renovation. part of renovation is converting from oil to gas. our contractors are putting in a buderus boiler and a unico system. now we are evaluating our options for hot water. our house (in PA) has 3 baths, dishwasher, washer, 4 kids (under 6 y.o), 2 adults (who feel 80 y.o.) we expect to have multiple appliances drawing hot water simultaniously.

simple question with i'm sure a not so simple answer... what is the lowest cost, most efficient and reliable option to heat our h20?

Ed_26

domestic hot water

An indirect water heater would be best - volume & price.

Brad White_169

Indirect

I agree with Ed. An properly sized indirect coupled to the correctly sized boiler will make hot water almost as fast as you can use it. I has volume to store as well so that you can use simultaneous fixtures.

"Tankless" heaters work best when near their points of use, can be fussy with flow (too little flow may be too hot) and the flow is finite. Run too much throught them and the water comes out cooler than you would like. If you sized a tankless for the worst case flow, the input would rival if not exceed your home heating boiler....

Go with the indirect.

jeff_95

thanks

Thanks for the advice - we're going with indirect...

Dave_23

Summer

How does one design and operate an indirect during the Summer months when the boiler (steam or water) is off? Is it still more efficient to run an indirect in the non-heating seasons than a conventional HWH or tankless?

ALH_4

water heaters

Boiler controls put the boiler into "warm weather shut-down" when the outdoor temperature exceeds the desired indoor temperature. This diables the heat but leaves the domestic hot water function enabled.

Efficiency depends on the boiler. If you have a low mass boiler, particularly a sealed-combustion modulating condensing boiler, it is still more efficient in the summer.

If you have a cast iron boiler, it would be less efficient in the summer than an instantaneous water heater.

However there are other reasons to use a tank versus on-demand. Most indirect water heaters are very resistant to deposits building up on the heat exchanger. Instantaneous water heaters can have problems with fouling of the heat exchanger. Plus, adding another fuel burning appliance increases the possibility that one will need service.

Dave_23

My setup

I have a WM EG-45 steam boiler. Would it be possible to add an indirect to this model and configuration? I'm preparing for a new HW heater to replace my aging conventional HWH.

Home Depot Employee

Not so Brad

"Tankless" heaters work best when near their points of use, can be fussy with flow (too little flow may be too hot) and the flow is finite. Run too much throught them and the water comes out cooler than you would like"

Not quite Brad, unless your thinking about the units 10+ years ago or the undersized inefficient units in the big box store.

Todays quality units; Rannai, Takagi or Noritz for example regulate and control the modulating burner to 1-3 degrees actual output of setpoint of the unit at verying flows within the size and performance peramiters of unit selected.