AIR-TO-WATER (A2W) HEAT PUMPS - DETAILS

Hydronic Emitters

Hydronic (liquid-based) Emitters are not specific or unique to heat pump systems; in fact they are the similar to those used with the most efficient gas boilers.

We use one three types of emitters for heating and cooling:

1. Radiant (floor heating/cooling)

2. Wall-mounted “Panel” Radiators (heating/cooling)

3. Hydronic Air Handler (“low velocity” forced air)(heating/cooling via ducts_

Choosing between these depends on factors such as:

  • new vs. existing (retrofit) house;

  • budget;

  • floor surface types (wood, concrete, marmoleum, vinyl, cork, carpet, etc);

  • square footage and air volume (cathedral ceiling or not)

  • basement vs main floor rooms vs upstairs bedrooms; and

  • cooling requirements (if any).

1. RADIANT

1a. Slab-on-grade Radiant (or mono-slab)

  • The most common type of radiant heat.

  • Pex tubing covered with 4-6” of concrete. Tubing should be 2-3” from surface.

  • Works well but not as responsive as other radiant types in small spaces due to the mass of all the thick concrete.

  • The mass of concrete is a benefit in larger homes with high ceilings or workshops with garage doors.

  • +/- $20/SF w/ insulation, tubing, concrete, and floor finish (radiant tubing component is $3-5/SF contractor installed).

Images of radiant floor heating installation with tubing on insulated panels, and a diagram showing a slab-on-grade configuration.

1b. Staple-down Radiant

  • PEX tubing stapled to sub-floor then covered with a <2 inch layer of lightweight concrete or gypcrete.

  • Very efficient, responsive & comfortable.

  • $12-20/SF installed; including tubing, concrete and finished floor surface.

Three images show the process of installing a radiant floor heating system. The first image displays orange tubing laid out on the floor. The second image depicts someone pouring concrete over the tubing. The third diagram illustrates the staple-down thin-pour method, highlighting heat flow directions.

1c. Aluminum heat plates on subfloor 

  • Heat plates stapled to subfloor and covered with 1/4" plywood; then wood, vinyl, marmoleum or other thin flooring material with good heat transfer properties.

  • The most efficient, responsive & comfortable.

  • $10 to >$18 per SF (DIY vs contractor install).

  • WarmBoard & EcoWarm are pre-assembled/ commercially available products we like ($15-20/SF installed).

1d. Under-floor (staple-up) Radiant

  • If aluminum heat plates (“fins”) are used then this approach may be compatible with 100-130F supply temps of A2W heat pumps.

  • Many homes with radiant heat may have staple-up without plates; these systems need 140-160F supply temps.

  • w/o plates: <$2/SF DIY install; $5-7/SF contractor installed.

  • w/ plates: <$7/SF DIY install; $15/SF contractor installed.

Radiant floor heating installation with heat plates and diagram

2. RADIATORS

Two white wall-mounted electric heaters in a room with wood flooring.

2a. Hydronic Fan Coils (heating & cooling)

  • Quiet and responsive

  • Requires 120v power for variable speed fan/blower

  • Can be mounted higher on wall or even ceiling.

  • Temperature control is via buttons on the emitters or hand-held thermostats.

  • PEX tubing is plumbed to each unit from manifold.

  • $600 to $1,000 (several sizes) for hardware only.

2b. Wall-mounted Panel Radiators

  • Hydronic (liquid-based) radiators that transfer heat passively via convection (no fan; so heating-only)

  • PEX tubing is plumbed to each unit from manifold.

  • Must be sized based on delivery temp of average 120F if used for heat pump.

  • Many sizes/shapes; including bathroom towel warmers.

  • $300 to $500 (several sizes) for hardware only.

Two wall-mounted white radiators, one on a mint green wall and the other on a wood-paneled wall.

3. AIR HANDLER (ducted)

  • A2W heat pumps can also be tied into ducted forced air systems using a hydronic (liquid-based) air handler for heating and cooling.

  • Compatible with 2” diameter mini-duct) system that works on the principle of pressure rather than air velocity. This makes it easier to install inside existing walls with minimal remodelling).

  • Can also provide HEPA-level air filtration, ventilation, humidification and dehumidification. Supplemental in-line duct heaters can be integrated too.

Arctic heat pump with insulated pipes in a utility room