Electric on demand

diy_bri_guy

Probably in over my head for sure. Remodeling a 100 year old house 32’x26’ and installing radiant floor heat. I have a 4 loop manifold on the 2nd floor with tubing above subfloor and engineered wood flooring. 5 loop on the first floor below subfloor all tile floors. 4 loop for the basement in slab. This means every floor will require a different water temperature I want to use electric on demand boiler or water heater and see a lot of negative things. Electric in the area isn’t very expensive and fuel is going to keep going up and I have options for “free” electric. So the manifold loop maximum flow rate is 1.6 GM x 13 loops = 20.8 gal max flow. Loops will be no more than 250’ at 8” intervals so estimating a 10 degree delta t. This gives me 104,000 btu requirement. This sounds way to high to me I have seen systems in the area that have more sqft and half this btu with on demand systems. Essentially the whole system is less than 3000’ so around 30 gallons or less I would think it wouldn’t take much. Any help is appreciated temps in the teens and my portable heater isn’t cutting it anymore.

hot_rod

If you really want electric I'd go with a small electric boiler like this. The size of boiler you need is based on a heat load calculation, try a free load calc at WWW.slantfin
1/2 pex loops usually flow .50- .65 gpm

diy_bri_guy

Thanks for the input hot_rod Heat loss calculated 20,349 btu @ 180 water temp that should get me closer. You answered my next question youngplumber thanks.

EdTheHeaterMan

diy_bri_guy said:

Thanks for the input hot_rod Heat loss calculated 20,349 btu @ 180 water temp that should get me closer. You answered my next question @Youngplumber thanks.

Give the kid an "Attaboy" for psychic abilities

hot_rod

diy_bri_guy said:

Thanks for the input hot_rod Heat loss calculated 20,349 btu @ 180 water temp that should get me closer. You answered my next question youngplumber thanks.

So a 6KW electric would give you 20,460 BTU per hr. What are your electric rates, on a design day 20KW X your rate, gives you an idea of cost to run

jumper

Similar situation has come up on this site recently. Forget hydronic and go radiant electric.
Easy to control each room. Also on this site problems with HHW are regularly mentioned.

diy_bri_guy

Thanks hot_rod doing the math on grid would be $25 a day that’s about $6 more that fuel oil is currently costing me where I’m renting during this fiasco. Maybe I will stick to propane combi or a coal/propane boiler with indirect hw. I don’t see being able to supplement the electric demand for the electric boiler.

hot_rod

Yeah, you need to look closely at energy prices in your area to make the call. Sounds like electricity, oil, or LP. That coalpail site allows you to input prices and equipment efficiencies. Upfront cost may be high, but an air to water heat pump could heat, cool, provide DHW with electricity

diy_bri_guy

Jumper I already have the track for the second floor and all the pex and transfer plates. I thought about electric in floor for the whole house have it for the bathrooms.

Zman

Your required BTU's are determined by the characteristics of your house and outdoor temp. The design of your distribution system uses the math you are referring to. You need to download a heat loss calculator like the one slant fin offers to determine your heat loss and boiler size.

What are your available fuel sources and their costs? I have never seen electricity cheaper than natural gas and it is not usually less expensive than propane and heating oil.

diy_bri_guy

Zman I used the calculator slant fin recommended and got 20349 btu. @180 degree water temp. Max water temp in my system would be 120. Natural gas is not available and after years of fuel oil I refuse to put it in this house. Propane is expensive I have been considering a dual fuel propane/ coal boiler to only use the propane at the beginning and end of the heating season. But I have a good constant water flow behind the house with enough elevation drop to run a 15 kw hydro generator. I’m in the process of patenting another power source that’s why I was considering all electric.

Jamie Hall

I don't understand the what water temperature has to do with BTU load. It does, of course, affect the size of the emitters -- but not the heat loss of the building. You can't run anything like that water temperature in a radiant floor, although you can run the boiler at that (though I wouldn't) and mix it down to what is needed.

Since you categorically refuse to use fuel oil (what do you use to power your car?), I can't imagine why you would want anything to do with coal. You do seem to have the potential for enough hydro -- assuming that you can get the permits -- to power an electric boiler, provided you don't go much below freezing in the winter. Streams have a way of freezing up.

diy_bri_guy

Jamie hall I’m not against fossil fuels by any means. I’m not looking to go green except in my wallet😂. I know I can’t use those temps the heat loss calculator recommended is for radiator heating and I just added the info it supplied. Propane is expensive oil sucks and natural gas is not available. Of all the fossil fuels coal is the cheapest to use in my area. I can probably dig a hole and find it myself 😂. It’s been really cold for the last week and the water still flowing strong. Flowed all last winter and past 2 summers. I’m sure ice will be an issue at some point. I don’t have nosy neighbors no permits needed I’m not gonna build a dam. Knowing what I need now you’re right not going to be able to power a boiler.

Jamie Hall

Actually, @diy_bri_guy , you may need a permit for that hydro. I'd look into that. In some states -- Connecticut for example -- a permit is required from the local Wetlands Commission for any work in a stream. And if the WOTUS regulation which is currently on hold at the Federal level is reinstated by the new administration, you will need a permit from the US Army Corps of Engineers, which will pre-empt local regulation.

Zman

How are you determining which fuels are more costly?
What are your local prices for electricity, fuel oil and propane.
Your perception of pricing may not be accurate.

PerryHolzman

Please note that the cost difference of the energy or fuel is only a part of the equation:

Installation and maintenance cost also has to be considered.

Electric may well be your cheapest overall source once you consider installation and annual maintenance cost.

Electric heating units and electric boilers are relatively cheap, and require minimal maintenance. Coal, Gas, Oil,Propane all cost more to install, and typically require annual maintenance - and may need to be replaced in 10-15 years (unless you buy the higher end premium equipment - and reasonable priced parts are available in 10-15 years when they need them).

Also, when considering electric heat: You may need to upgrade your electric service and install a larger breaker panel (or a 2nd dedicated breaker panel for the electric heat if you can get off-peak rates).

I once wired an electric heating system where the utility installed a dual meter electric service (normal service and off peak heating service) at no cost and I installed an off peak electric heat storage register in each room of the house. These registers were full of ceramic bricks which heated up at night and contained enough heat to keep the rooms warm all day. That's the biggest wiring job I have ever personally done (I think I used about 500 ft of 3 wire 8 gauge cable and installed a new 200 Amp breaker panel just for the heating system). I did it as part of my reduced rent to share the house with the owner as I was between jobs at the time.

Get some quotes, consider all factors... and see where things fall out.

Perry

jumper

diy_bri_guy said:

Jumper I already have the track for the second floor and all the pex and transfer plates. I thought about electric in floor for the whole house have it for the bathrooms.

You can run all your radiant floors at minimum temperature. That will make system simpler for you and in future you might use heat pump. Any room sometimes uncomfortable can be supplemented with direct electric radiant.

Since my business was hydronic I'm a bit prejudiced against electric. But this website and other experiences indicate that stuff goes wrong and there aren't always competent technicians anymore. Premonition is that modern complex systems will someday bite homeowner.