I wonder about your BTU figure. Electrical resistance produces 3.412 BTUs per kw. If your boiler is 20kw, that would peg its output to about 68,000 BTUs. Maybe a typo when you added the 1 to make it 168k?

Are you thinking about an air to water heat pump or were you planning on putting in ducts or mini-splits? If using air delivery, that will give you air conditioning too.

I think most air to air systems max out at 60K BTUs, 5 tons, so you're right at the threshold of maybe needing two smaller systems if going the conventional split system approach. Take your advice not from me but from HVAC experts, I'm just a fellow homeowner.

Heat pumps in most circumstances will use one-half to two-thirds less electricity than your resistance system now in place.

Thanks, Elmer, for catching my mistake - I just checked the label on the boiler and it is 68,200 BTU. I'm not planning on putting in any ducts or mini-splits, just trying to heat the water in my hydronic in a more efficient manner. Two years ago, I did get a quote to do what you suggest, and I decided that it was too expensive:

(2) HAIER 4U36EH2VHA (30,000-40,000 BTU ea),

4 Indoor heads, Line sets, Line hides, disconnects, breakers, wire, condensate line etc. $14,368.75

Installation of system

$9,635.80

The primary advantage of this system is that it would supply AC also; the primary disadvantage is that I prefer radiant heat.

You could convert to an Air-To-Water or a Geothermal Water-To-Water heat pump that will do everything you want to do and more. Hydronic heating and air-conditioning and domestic hot water (DHW).

It will be expensive but you already have the electrical entrance and a backup boiler installed in place. You would not need ductwork.

There are substantial incentives in NY to offset some of these costs. The operational savings might be very high. Worth looking into to, either to rule in or out.

What water temperature does your existing boiler have to deliver at design temperatures?

IMPO

SR

current temperature is about 150F. I am interested in the air-to-water, but don't know how to proceed.

To my knowledge, radiant cooling (running chilled water through in-floor pipes) is neither effective nor very common in the US. A major issue, besides the fact that heat rises and the upper levels of room air will remain hot, is that in much of the US, humidity removal is as much a comfort-producing feature of traditional AC as is air cooling. I would expect that a chilled floor in a humid room would get wet - that removes some water vapor from the air but causes other obvious problems, potentially major ones.

If you want to fill the pockets of your local tradesmen by going with the most expensive alternative and spend two or three times more, you could consider the ground source approach.

I guess we are getting our stories mixed up. If I heat my radiant pipes from the heat pump, I would not use them for cooling - this is a heating solution only. When I got the Mini split quote, we had just gone through a hot spell - temperatures over 80F for 3 days! But I decided cooling was not necessary because it went down to 60 at night. And I don't plan to use a ground sourced heat pump, that's why I asked about an air-sourced one.

An Air-To-Water heat pump would be rather expensive and you would not be using it to its full potential. The higher the water temperature an Air-To-Water HP would have to produce, the lower its efficiency. That could be dealt with by adding lower temperature panel radiators but not likely worth the trouble in your case.

I think you would be better off and better served by looking more into the mini-split options.

Just for clarification, I would not usually recommend in-floor radiant cooling for residential applications although they can work. In-floor radiant would be more appropriate in a commercial/institutional setting where humidity and Dew Point is better monitored and controlled.

Floors would be zoned out for cooling in residential with chilled water fed fan coil units for both heating and cooling. They are fed by insulated piping that is a must to prevent sweating and fan coil units that collect and deal with condensate in air-conditioning mode much like mini-splits or any other fan coil units. You may have already seen them and had no idea they were hydronic, water fed as they would look like conventional mini-split heads or central fan coils.

IMPO

SR

Again, I was never planning on cooling the radiant pipes, just heating. Any cooling would be done with a mini-split and I decided that that wouldn't be worth it.