50 gallon natural gas water heater with hydronic heating - opinions.

[atvjoel]

Building a small duplex. 2 units 768 sq ft. Small town. One plumbing/heating company "booked until December" another one "call you January". Another one sorry we are booked I will call you if something opens up.
Could go forced air (we dont need AC in my climate in Alaska so forced air not hard) but #1 theres only 1 local sheetmetal company that does HVAC ducting locally and with hydronic since I already have the new 50 gallon water heaters seems the way to go but obviously traditionally are with boilers so I can get people barking at this idea. Before I get judged duplex has ICFs, 3" foam ext wall including rim joists, attic (plus blow in). Triple pane windows. By all means could probably heat the place with a candle but is there anything in the plumbing code that prohibits this? I cant really find answers dont mean to be lazy.

Building the system wont be hard. Small units and well insulated really could get away with one zone per unit. Its really my only option and its affordable. One unit a 2/1 the other unit 1/1 so we are not talking high hot water usage each unit has their own water heater.

Several people have built these systems on youtube with double the sq footage for one water heater. One guy said his only kicks on 3 times a day and he is in northern state. Urethane foam, triple pane windows, ICFs, half his sq ft I think this is plausible.

Does anyone agree with this article? https://baileylineroad.com/hydronic-heating-with-water-heater/

 

[atvjoel]

Baseboard Hydronic heating

 

[atvjoel]

This guy had his house permitted and inspected along with his hot water hydronic heating system and it passed. The difference with my system is I will use baseboard and also use it for hot water to the units fixtures so constant fresh water will be coming into the system.

 

[steveray]

M2004.1 General. Water heaters used to supply both potable
hot water and hot water for space heating shall be installed in
accordance with this chapter, Chapter 24, Chapter 28 and the
manufacturer’s instructions.

 

[mtlogcabin]

since I already have the new 50 gallon water heaters

Are they gas or electric and what is the recovery rate of the water heaters would be the big question. The Delta temperature difference between the water coming in and the temperature of the water you want to achieve will determine if what you want to do will work.

SECTION P2803
WATER HEATERS USED FOR SPACE HEATING

P2803.1 Protection of potable water.
Piping and components connected to a water heater for space heating applications shall be suitable for use with potable water in accordance with Chapter 29. Water heaters that will be used to supply potable water shall not be connected to a heating system or components previously used with nonpotable-water heating appliances. Chemicals for boiler treatment shall not be introduced into the water heater.

P2803.2 Temperature control.
Where a combination water heater-space heating system requires water for space heating at temperatures exceeding 140º;F (60º;C), a master thermostatic mixing valve complying with ASSE 1017 shall be installed to temper the water to a temperature of not greater than 140º;F (60º;C) for domestic uses.

 

[Paul Sweet]

Do a heat loss calculation to verify that the water heaters have at least 15,000 spare BTUH capacity (equivalent to a 4500 W electric water heater element) for domestic water on a design day. It would be safer to size the radiation for 140 deg. water in case a tempering valve failed.