heating with kickplate heaters

hammerstone

Hi All,

I have a house heated by floor louvers fed from two separate 100,000 Btu/hr furnaces in the crawlspace, each furnace heating about 1/2 of the 2400 sf of space. Both furnaces are from the 80's, and getting long in the tooth. (the house was built in '64.) I've got some quotes to combine the ductwork and replace the two furnaces with one, (and add an AC coil for the wife), but it is looking like big bucks (over $). One idea that i might be able to handle myself is put floor-kit kickspace heaters in the existing louvers for one of the furnaces and supply them all from one water heater. This would eliminate a lot of clutter in the crawlspace (supply and return air ductwork, one or both furnaces, clean up some of the electrical spaghetti that has accumulated over the years, etc). This could also save some money i suppose, as i could do a lot of the work. eventually i'd have to add some AD, so a few well placed mini-splits.... But first the heating situation.....

More details: The hot water demand for the kitchen and laundry room is supplied from one water heater (original to the house) also in the crawlspace, while the 2 bathrooms at the other end of the house are supplied by a water heater in a closet in the living space (recently replaced with a new unit). So the idea would be to replace the old crawlspace water heater with a higher efficiency and larger capacity unit (I own a Polaris 50 gallon 150K BTU unit) and have that supply both the new kickspace units (a total of 10 of them) and the laundry and kitchen demand as well. If this worked, i'd consider expanding the idea to the other half of the house, either with a second water heater or using the Polaris above.

A few questions:

has anyone done this type of installation? thoughts?

are the joist installed kickspace type heaters (and under cabinet kickspace units) suitable for heating an entire (or in this case 1/2 of) house? The original home plans show a demand of ~50,000 Btu/hr for each half of the house (after duct loss, efficiency derate, elevation derate, they used the two 100K Btu/hr units).

It seems that these kickspace units draw inlet air through the same grate as the heated air (albeit there must be a divider in the unit); any concern about drawing in heated air and short-circuiting the unit?

What would the plumbing look like for the water heater? I'm a little concerned about having potable water sitting in the lines of the heating loops all summer when there is no heat demand, or with using the water that goes through the heaters as potable after it's been through. Anyone have a schematic of how to set this up?

The existing Polaris should be able to supply the entire house heating demand (roughly, 150K Btu/hr loses 6K Btu/hr from efficiency, then need derating for elevation). Another option could be to just use the Polaris for the heating demand, and get a smaller water heater for the kitchen/laundry demand.

These kickspace units seem to be about $200 each; i'd have to run a lot of electric for the fans, but that wouldn't be too hard, especially if i lost the furnaces i would have those receptacles available. So for one furnace replacement, say $ in heaters, $ for the Polaris (which i already have), probably another $ in tubing, circ pumps and controls, and then estimate another $ for a plumber to connect everything. That would put me at about $ if i don't count the Polaris. Did i miss any big ticket items?


It's a long post for a newbie, i appreciate anyone that actually takes the time to read it all and provide input. Or point me to other resources. thanks in advance.

hammerstone

meant i would have to add some AC, not AD in the first paragraph.

mattmia2

If you want to convert to hydronic, get a real boiler, either a conventional boiler or a mod con and use panel radiators or baseboard radiators to heat the space. Or put the effort you'll have to put in to learning how to engineer hydronic circuits in to learning how to engineer and fabricate ductwork.

Zman

Do not under any circumstances install an open hot water system. They are just plain not healthy.

I am curious why you consider the hot water heater project a good DIY project yet are steering away from forced air DIY?

It either case you need to do an actual heat loss calc. Spoiler alert, the whole house is probably <50K.

To combine the furnaces, you would need to learn a bit of math and then have a local duct fab shop make fittings for you. Make sure to stock up on band aids, that metal is sharp.

hammerstone

Zman/Mattmia thanks for the input. sounds like a not well accepted (at a minimum) technique. i am considering the hot water heater DIY because i can run tubing, but i can't make ductwork for a DIY. I didn't realize there might be a fab shop where i can get ductwork fabricated. Maybe that is the opportunity. or i just keep saving money and hire it done. I have the heat loss calculations from the original house, which was done room by room and louver by louver, so i already have that, which to me meant all i had to do was convert the heat required from the forced air louvers to these kickplate heaters. That comes down to a flow rate of liquid and temperature drop, which the kickplate guys (Beacon/Morris) already have. So i'd do mdot x cp x dt to get the heat at each louvre, and then run it through the whole system. i assumed it would need multiple zones to get there.

Do you have any references that lay out the un-healthy risks of an "open" system? here is at least one company that seems to think it is fine, although they do have a solution for circulating water through the lines. https://www.radiantec.com/about-radiant-heating/open-direct-system/

sounds like i'm biting off more than i can chew regardless....

JUGHNE

If your duct work is in reasonably good shape, you could consider just changing the 100,000 furnaces to ones about 1/2 that size.

With the efforts of room by room heat loss done and actual louver delivery there is a good chance that the duct was correctly installed.

AC in each could be optional.....do not over size for cooling.

2 smallish systems are much more efficient than one large one.
You get the effect of zoning without the baggage that comes with one huge furnace.
You can probably leave the ductwork alone, just change the furnaces. IIWM, I would have an AC coil installed in each.
(again not oversized) Then future outside units optional.

Where are you located?

Zman

There is a lot more to the hydronic option than just running tubes.
I have first-hand experience with open systems. They turn into slimy bacteria farms. I feel a little sick just thinking about the last one I worked on.
Some online radiant companies have a horrible reputation for promoting open systems and then threatening folks that speak out against them. I can remember the name but I think it rhymes with Radiant Wreck.

hammerstone

jughne, i'm in northern New Mexico, Los Alamos to be exact; we're at 7700 feet elevation. thanks for the comments about staying with 2 units. The quotes i had to replace two units and include 2 AC coils and outside condensers (including tax at 6%) were:

$ (~$ each) for 80% Trane S8X1C100M5PSAA furnace and Trane 14 SEER condenser 4TTR4048L1000A

$ (~$ each) for 80% Trane TUD2B060A9V3VB furnace and Trane 16 SEER 4TTR6036L1000A

$ (~$ each) for Trane 95% TDHMB060CV3VB furnace and Trane 20 SEER 4TTV0036B1000B condenser.

I also have a quote to convert to single unit by tying the existing ductwork together at one furnace, but having two zones, and adding one condenser unit (again with two zones)

$ for Trane S9V2 furnace with 17 SEER condenser, and modifications to the existing ductwork.

All of those were more than I thought. This house is on a crawlspace, but in most places one can stand up (albeit stooped) and there isn't any place where you'd have to crawl. I understood from the Trane website that a S9V2 including installation would be $-$, so i guess these quotes are about what i should expect. any thoughts on installed prices? i know it varies by location, but any thoughts would be appreciated.

Both the existing units are still working, but they are old. and not very efficient.

Zman, thanks for the comment; i'd hate to start a bacteria farm in the crawlspace.

Jon_blaney

Have you given any thought to window AC? Todays units are much lighter and more attractive that those of ten years ago. They are easy to zone and cost way less, maybe 10% the cost of central system. How much do you actually need cooling? I went through a similar evaluation and decided to go the window unit route and keep the furnace I have. After three summers, I am convinced it was the right solution. My oil furnace has a lifetime warranty on the heat exchanger so it can be rebuilt. This may have colored my decision. What fuel do you use? Are you happy with that choice?