Basic question for new-build hydronic heating

OhioBarnBuild · 5:25PM

A few years ago, I got a lot of good input from people here on my hydronic heating system for my shop. The tubing is in the slab and after three years, I’m very happy with it. It is now time to design a system for the new house on the property, which is a different animal. I used LoopCAD to design the system for my shop and will be using the latest version for the house’s system. Construction will start in a couple months and it will be 2600 sq ft, with a 9-foot basement under 1000 sq ft and a 4-foot crawl space under the remainder. I’ve done a lot of searching on this forum and the internet in general and I’m having difficulty finding relevant information that is less than ten years old. Since I’m sure technology has improved since then, I need some help with basic design. Starting with the most basic, is there an installation method that is preferred for new construction, i.e. in-floor vs. under-floor? Once I know that, I will come back with more specific questions.

Additional info: Central ohio, propane heat, plan to use a combi-boiler for heating and DHW. The main floor will have LVF throughout with area rugs here and there over the LVF. Tile in the bathrooms. The basement and crawl space will be primarily used for storage so they don’t necessarily need to be as warm as the rest of the house in winter.

While I want to have an efficient system, I don’t want to add details that are technically helpful but have a 15+ year payback period. A local Warmboard contractor wants $40K for the installation, so that’s not gonna happen. I’ll probably do the installation myself (possibly with a helper).

Thanks in advance.

hot_rod · 5:38PM

The basement will have tube, I like to do 6" on center for fast response and lowest possible SWT. Insulation below. Someone, someday may want to finish that space, tube is inexpensive

For the framed floors either plates from below, plates or a pre-manufactured dry system on top.

Or a 1-1/2" thin slab on the framed floor. Double the bottom plate your walls if you go with a thin slab. It depends on floor covering. If you plan on any nail down hardwood, thin slabs add some challenges. Tile, floating hardwood, carpet works on thin slabs.

Slower response, a bit more thermal mass to even floor temperatures

Radiant walls or ceilings.

Pros and cons to all the methods.

If you are doing the work yourself lay foam or concrete insulation blankets in the crawl to make it more pleasant to work down there.

The LoopCAD will indicate the tube spacing, generally 8" and lengths as well as SWT. Or if you have high load ares that need supplemental.

Panel radiators are another option. Really no need for radiant floors in bedrooms, typically carpeted, mostly covered by furniture.

My next build will be a blend of panel rads and radiant floors in tile areas like bath and kitchen.

What is your AC plan?

OhioBarnBuild · 6:21PM

Thanks for the quick response! Lots of good info there.

It sounds like no single approach is hands-down the best one, which is good to hear. I'm leaning toward the thin slab approach for the living area. We won't be using hardwood flooring anywhere and just the thought of installing all that tubing overhead from the basement/crawl space makes my shoulders and back hurt.

We're going to put a concrete floor in the crawl space also and will have rigid R-10 under both it and the basement floor, as well as around the perimeter.

We plan to use a central AC unit, mainly because I'm not aware of a good alternative. I familiar with mini-splits, but I'm not quite convinced they're as awesome as some people on the web make them out to be.

Alan (California Radiant) Forbes · 6:41PM

Ecowarm is a good alternative to Warmboard. It has a thinner aluminum skin which translates to warmer water temperatures, but it’s quite a bit less expensive to buy. And it’s still plywood and not particleboard like some of the others. However, with any preformed board product, you’re stuck with their spacing. I like tight tube spacing at exterior walls and then wider spacing as you move inside and you can’t do that with a board product.

An alternative is something like Gypcrete. It used to be $3/[], but it’s probably more now. Great sound insulation as an extra! And freedom to space you’re tubing any way you want

Yes, radiators are an option, but I sure like warm floors.

hot_rod · 7:33PM

I would stay away from lightweight mixes, those with plastic beads or lightweight aggregate.

Gyp pours are not good for tile applications and the gyp comes apart if it sees any moisture. Even with a sealer. It's original intent was sound and fire barrier for hotels.

This mix works well down to 1-1/2" pours, the Youker Mix

1 cubic yard 3000 psi

517 lbs portland

1639 lbs concrete sand

1485 lbs #1A 1/4" crushed (pea gravel)

4 oz air entrainment agent

15 oz Hycol water reducing agent

1.5 lb fiber mesh

51 oz superplasticizer

20 gallon water

Send this list to the batch yard you are considering

You can wheelbarrow this or a small concrete pumper, 2" hose even

PVC control strips in the interior door ways. Break the area into small mosaics with these control strips. PVC drywall trim works well for this

Poly film over floor sheathing as a bond breaker. Tape the seams

Duck tube below wall plates, mark plates where they can be safely drilled for plumbing and electrical work.

Mineral oil or WD 40 on any sleepers for hardwood nailing.

3/8" pex tube

Plan on some of the fine "road map" cracks even with all precautions.

Also pay attention to joist sizing, no bounce in the floor! there are a lot of I joist options these days.

Put a one size larger plate down 1st. Frame wall on top of that. This gives you a screed board everywhere.

A drone is a good option for getting pics before the pour. Pex unwinder from shop stool :)

Our next Idronics issue, Avoiding Common Mistakes, this graph regarding light weight mixes

Basic question for new-build hydronic heating

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