Thought myself into a corner - need help sorting out a boiler, DHW, etc.

Richard Miller

I built a well insulated 2,800 sq. ft. home. 1,600 living quarters, 1,200 shop/garage which will be heated and cooled and used extensively. 10’ ceilings throughout. The roof is insulated, so the attic will be somewhat conditioned.

Because it is in Missouri, I was tempted to skip the radiant floor, but my wife insisted two zones, I put it in. (“After all these years of you passionately preaching how good it is, you have to put it in your own house.”) She made a good point.

So I put the tubing in the concrete floor. Four zones, but I can easily change that to two zones, with the house being on one zone, and the shop on another. But I probably won’t, because I want to be able to control the living room/dining room/kitchen separately, because there will be a tiny woodstove in there that we will use mostly for ambience, but will also contribute heat.

I ran 1” PEX to the water heater closet, which is 25 feet away from the boiler location.

I was planning to put air-conditioning in the conditioned attic, but realized that I could put in a ducted minisplit heat pump for only a few dollars more. A regular minisplit in the shop. One of the advantages of this equipment is that I could run it all on my 9500 W inverter generator.

Now I have triple (or is that double?) redundancy for my heating. Radiant floor for the primary, heat pump for back up, and a tiny wood stove for supplement/emergency.

I also have gas and electric hook ups for the water heater, in case I ever need it.

OK, by now you know that I am certifiably nuts with all the redundancies. That would not be used to any of my friends.

So here’s my dilemma. With no ceiling in, (meaning that it is open all the way to the insulated roof line) and with the two doorways between the house and the shop open,I have three of those little plug-in oil filled radiant 1500 W heaters running for temporary heat. This morning it is 31° outside, and 63° inside.

I was going to install a Lochinvar Knight, that would then also run an indirect water heater.

With a 10 to 1 turn down on the 85,000 BTU unit, that will get me down to 8500 BTUs, but have the full capacity available for domestic hot water production. Oh, I plan to have a cheap electric water heater in the shed, in case my heating system goes down for an extended period of time, to where I can quickly swap out the indirect water heater for an electric, and keep showering.

But now, with this real world experience happening with those little heaters, I’m wondering why I’m going to that expense? This is south Missouri, so electricity is fairly reasonable. My gas has to be propane, because I am very rural.

Again, why am I going to that kind of expense with this small of a heat load? So I start going other directions, and I lose the modulation/efficiencies/controls. By the way, I do not want to install anything that penetrate the roof if I can help it.

Maybe I should buy a cheap Weil-McLain mod-con? (I still remember installing some of the first GV Golds on the western slope in Colorado.)

I know I’m overthinking all this, and by now you know it too. But can you help me with brainstorming some solutions?

Oh, another obstacle. Because I am no longer in the trade, and because my dear Papa has went over to the other side, I have limited access to normal trade channels. I do have access to a few. It’s a weird feeling to have been in the trades all those years, and now to not have access.

Anyway, what do you think? Here’s a couple of screenshots from my Manuel J.

Richard Miller

I missed a couple of notes in my “book”. LOL

There is no such thing as inspections where I built. If it works, and it is safe and it makes sense all around, I can do it. Also, I should be able to do any repairs/maintenance. I have the skills, and most of the tools. Shucks, I still have my W-M branded Dwyer U-tube manometer that W-M sent out for the high altitude issues with the GV Gold boiler back in the early 90s. Now that’s a blast from the past isn’t it? Anyone else remember those?

Richard Miller

just thought of something else that I forgot. I thought about putting in an electric water heater for the domestic hot water, and then another one to heat the house, and just play with things until I know what my heating loads are actually going to play out as. But, I cannot run to electric water heaters on my generator if there’s a power outage. So I feel vulnerable with that. Again, overthinking it? Yes. But I’m trying to build a house for the rest of my life, and one that has a lot of redundancies

ethicalpaul

I don't think an electric water heater will heat your house.

A heat pump water heater in heat-pump only mode can run on your generator

Richard Miller

https://forum.heatinghelp.com/discussion/comment/1826258#Comment_1826258

yeah, I should have specified the electric deficiency would be picked up by the heat pump.

Jamie Hall

When you find yourself in a hole, stop digging…

You have set yourself up with an excellent set of options. Not only that, but you are in a position to get real world data on your house before you do anything!

Step back a bit and fully define what you need to have for heat and other conditioning, what the options are, and their benefits and disadvantages. Make a nice list. I think if you do that you will find that one or two will stand out as the way to go forward from here…

Kaos

Some of this depends on your local energy costs and how common power outage is.

Around me per mmbtu, propane is only slightly cheaper than electricity, so operating cost is pretty close to resistance. If similar in your area, your best bet for the floor heat is a resistance boiler. As long as your heat pump can supply the bulk of the space heat, keeping the floors a couple of degrees above ambient should not cost all that much even with resistance.

If your popane costs are cheap enough, the other floor heat option is a combi rated tank water heater with something like a Taco X-block to provide the space heat. For the low load you are looking at, even the smallest burner will easily handle your hot water and floor heat.

If power outage is common, you want something that doesn't need electricity to keep your place from freezing. Generator is nice but they have the nasty habit of not turning on especially when you are away. The best options for space heat backup is something that doesn't need power, that is usually a through the wall vented propane heater near your utility room that would also keep your pipes from freezing.

hot_rod

With the load that low, maybe an electric boiler is an option.

Plug in your numbers here.

I've hot rodded electric water heater tanks with two 6,000 W elements, that 20,460 btu/hr. Or close to 41,000 btu/hr if you run two 30 amp circuits to power both elements at the same time.

Direct vent LP water heaters may be an option, probably in the 35,000 btu/hr. output range.

I think the CombiCors are available in a variety of styles, under the Laars name, those were 65,000 btu/hr I believe

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