Heat Source for in floor

red35x

I am utilizing in floor heat for a 24 X 26 with upstairs and is well insulated. This is a self contained system so use is for in floor heat only. I have 3 loops of 220 foot pex tubing and started with a 30 gallon electric hot water heater. I use it only on time of use(7 pm to 7am) so rates are approximately 30 % of standard rate. But by the time the power company adds on the delivery charge, customer charge, etc. it jumps to 60 % of standard rate. The monthyl cost is approximaely $ 200. It is a self contained system and struggles to keep temps in the mid fifties. Due to cost when installed 15 years ago, i went with a hot water heater and cost to heat was at $100 month. So looking to upgrade and considering choices.

A. Install a tankless electric boiler. (Higher cost for boiler and will take approximately same btus and montly cost will remain nearly the same.) Are the boilers more efficient than the hot water heater?

B. Wire the hot water heater so both elements heat at same time. (Probably the least cost wise but effective except for monthly electricigy cost as I will be using the same or more kw). Will building codes allow this?

C. Install natural gas boiler. Will probably be most efficient but much higher initial cost. I would settle for a good used natural gas boiler but difficult to find a good used in the smaller size that I need.

D. Some people have suggested a tanless hot water heater but after reading all the information on this site, I will not consider it.

I have spent hours on this site and commend all for providing all the information I have obtaiined. Congrats to all and looking forward to suggestions.

THANKS

GGross

A: any type of electric heat where the elements are fully inside the heated building are 100% efficient minimum, more if it is a heat pump.

B: I don't know if your code allows this, but it won't change anything, what are you hoping to gain from this?

C: can't be more "efficient" than electric, it will probably be much less expensive for the fuel however (not including utility company charges or installation cost)

D: don't use a tankless water heater

Now I have a question. What part of your system do you not like?

hot_rod

Accurately compare the various fuel costs first. Delivered costs!

A tank type gas WH, maybe 78- 80% efficient. Plus a flue and combustion air requirement.

https://coalpail.com/fuel-comparison-calculator-home-heating

red35x

A. Not a heat pump.

B. Hot water heaters only utilize one heating element at a time. The upper element is utilized until the water temperature falls below a certain degree and then the lower element is utilized. Wiring the lower element direct utilizes both heating elements for faster recovery time for in floor heat temperatures.

C. Electric seems the way to go in regards to total cost.

The only part I do not like is the recovery time of temperatures as I only use the system in off peak times for the lowest prices per kw. The room temp during the week gets to low 50s and pending outside temps, will only rise to 56 ish overnight(off peak heating hours). I usually leave the heating system on during weekends to recover inside temps in the low to mid 60s. Therefore, I have explored wiring the second heating element direct so both run at the same time.

Thanks for the response and reference to the heat comp chart.

GGross

Your recovery time will very likely always be that way if you only run the system for half the day. Radiant floors work best if they maintain a constant temperature. your water heater very likely has a lower btu rating than some other electric equipment, but with a radiant floor you will also be limited somewhat by supply temperatures, and the time it takes to heat up that much mass. Have you ever tried just setting it to a constant temperature all day and see how much more money it costs, even just a 5 degree setback overnight? Also if you were to swap out to gas, and run the system constant to maintain a temp you might not see savings over your current bills, because it will take more energy to maintain 70 degrees all day, than to maintain 55 for half the day and turn off the other half. Honestly your cheapest bet if you just want to heat the space half the day would be something forced air, electric unit heater or the like. I would seriously just set the stat for a constant temp and see how much it costs if it were me though, seems like a lot of your bill is in minimum charges etc.