Water Heater for Building Heat and Hot Water?

maine_way

Hello All,

I am considering a Phoenix, PH199-80, Stainless Steel NG Water Heater as the boiler for my building. I am able to get a new one for half price, and I would like any advice on pros and cons of this approach.
The radiation I am using in the building is a mix of cast iron baseboard and radiant heat, perhaps with one panel radiator.

The hot water tank in this model is set up with a heat exchanger with auxiliary ports as well as connections for domestic hot water, allowing it to serve both functions.

Since I am planning to have different types of radiation with different water temperature requirements, does this setup help with that in comparison to a wall hung condensing boiler? Does the hot water tank work as a buffer tank?

What are the advantages and disadvantages of this system? The other system I am considering is a dual 100k BTU wall-hung boiler system with primary and secondary piping, such that the second boiler would only cycle on when needed. This would be more efficient since the shoulder seasons would only need one boiler, and the second boiler could kick in if hot water demand was high (building has 4 showers and a dishwasher). Also, the added benefit is redundant system if there is one breaks, allowing time for repair.

Any thoughts are appreciated!

Shawn

Jamie Hall

Nice water heater. Shame it's not a boiler.

It is sometimes attractive to think of a water heater as a heating boiler. They are not the same. They are not designed for the same purpose.

Just don't do it.

Do this right: first, for your heating system, do a comprehensive and accurate heat loss for your structure. That will determine the size boiler which you need. You can't get the size by guessing or rule of thumb. Then figure out what temperature water you need to supply. Radiant requires, as you note, very different water temperature from your baseboards and panel radiators. If you can get by with return temperatures below 140, a mod/con may make some sense. Otherwise it doesn't. Then pipe and control the boiler to get the right temperature water to where you need it when you need it.

You could run an indirect for your domestic hot water off the same boiler, or you could run a separate hot water heater for the domestic hot water.

Just don't run a water heater for the building heating.

psb75

Don't use the water heater as a boiler. I like your second idea much better--the twin mod con boilers. I'll bet you could even downsize to 80 or even 60 mbtu boilers.

mattmia2

I think there is a phoenix version designed to be a boiler. use that and use a hx or possibly an indirect depending on your load to make hot water. Don't try to use system water as dhw.

maine_way

Thanks guys for the very clear direction. I will abandon the idea of using a hot water heater for a boiler too. Jamie, thank you for taking the time to explain in detail the how and why. I will follow you guidance here.

Rich_49

Jamie Hall said:

Nice water heater. Shame it's not a boiler.

It is sometimes attractive to think of a water heater as a heating boiler. They are not the same. They are not designed for the same purpose.

Just don't do it.

Do this right: first, for your heating system, do a comprehensive and accurate heat loss for your structure. That will determine the size boiler which you need. You can't get the size by guessing or rule of thumb. Then figure out what temperature water you need to supply. Radiant requires, as you note, very different water temperature from your baseboards and panel radiators. If you can get by with return temperatures below 140, a mod/con may make some sense. Otherwise it doesn't. Then pipe and control the boiler to get the right temperature water to where you need it when you need it.

You could run an indirect for your domestic hot water off the same boiler, or you could run a separate hot water heater for the domestic hot water.

Just don't run a water heater for the building heating.

Voila ! https://www.htproducts.com/versahydro.html

OMG , it's a boiler now . RELAX , the dinosaurs are extinct .