Radiant Floor system in Reno, Questions & Boiler ? (Newbie)

UT65

Hello All,
Reno of a 1875 Row Home/town house... 2nd fl (2) rooms = 243-sqft and 1st fl ( open concept 362 sqft, I have been estimating on 640 sqft total though the total are about 605sqft.

• 2nd floor will be under floor between joists mounting with floor insulated, its just 1 bedroom and bathroom, no door to bedroom on 2nd floor at top of stairs.
  
• 1st floor walls been removed and beams set for open floor plan
  

The first floor has a wide range of flooring issues with about 2.5" of average difference from one area to another, so I was thinking of black paper and PEX and then still debating sleepers and then gypcrete or looking at aircrete for lightening up the weight for the old floor system, which is why I was looking at sleepers. In either case has anyone ever used or seen used aircrete in the floor for leveling compound, I know it has great r-Value, not sure if that will work against me. Your thoughts on the Aircrete vrs gypcrete?

next question has to do with a boiler system. I have read that for small systems electric heat pump water heaters can be used, though I have also read other not a fan.

Some information, I gutted the place restudded the walls and installed R-15 Rockwool comfort batts with new drywall, the 2nd floor ceiling I installed 2 layers of R15 for R30, because no R30 mineral wool in 24" batts to be found. The reason I note this is because after doing all this a signal LG floor standing A/C rated for 10,000 BTU's set on the 2nd floor has been keeping the place comfortable at 73deg and cycles off and on throughout the day and stays mainly off at night while under the current reno.
Located in PA at about 1,600ft ele. We have been hitting 90 and high humidity

The calcs say 29,000 BTU's for A/C and 17,600 for heating using the supplyhouse.com calc, I get the same from a few other online calcs also.

Being the heating system will be radiant floor, and the fact that when I move out in a year or so I want to rent it, I was trying to keep the units all electric, So I was thinking of using a 80gal heat pump hot water tank for the boiler, there are no other baseboards or elements the unit would be asked to service, a second hot water heater would be for the domestic water.

Looking for suggestions and thoughts,

No lp gas and I would prefer not to install a propane tank or oil.

Zman

Any floor leveler with a high R-value is not going to work well when it comes to transferring heat. Gypcrete works well but the weight may be an issue. You could level the floor with a lightweight product and then use a panel system like warmboard on top https://www.warmboard.com/warmboard-s.

Heat pump water heaters work by taking heat from the space around the heater and transferring it into the water in the tank. If you are stealing the heat from the space you are trying to heat, well, you see the problem...

I small electric boiler might be a good answer for a little system like yours.

Hot_water_fan

Impressive insulation! This is not a great application for radiant floors, I’d stop you there: you have a well insulated, small, row house you don’t plan to live in long AND you have plans to add AC. I’d go with a ducted heat pump and save yourself a bundle.  Also, I’d get a pro to do your load calcs - if you have a 10,000 Btu unit cycling during the summer, your cooling load isn’t 30k Btu. 

Edit: your heat loss is also probably way off as well - I live in a 1300 sqft row house with zero insulation that has a heat loss lower than yours. The shared walls really save energy, it’s a good thing!  

UT65

Zman said:

Any floor leveler with a high R-value is not going to work well when it comes to transferring heat. Gypcrete works well but the weight may be an issue. You could level the floor with a lightweight product and then use a panel system like warmboard on top https://www.warmboard.com/warmboard-s.

Heat pump water heaters work by taking heat from the space around the heater and transferring it into the water in the tank. If you are stealing the heat from the space you are trying to heat, well, you see the problem...

I small electric boiler might be a good answer for a little system like yours.

Zman,

Thank you for the input and the Warmboard link, depending on time and price this might be a good solution to the first floor for me.

Do you have a specific electric boiler in mind? I am trying to figure this part out.

again Thank you...

Jamie Hall

I completely agree with @Hot_water_fan on this one. You will be best served with a heat pump, assuming that whoever does the sizing and installation knows what they are doing.

UT65

Hot_water_fan said:

Impressive insulation! This is not a great application for radiant floors, I’d stop you there: you have a well insulated, small, row house you don’t plan to live in long AND you have plans to add AC. I’d go with a ducted heat pump and save yourself a bundle.  Also, I’d get a pro to do your load calcs - if you have a 10,000 Btu unit cycling during the summer, your cooling load isn’t 30k Btu. 

Edit: your heat loss is also probably way off as well - I live in a 1300 sqft row house with zero insulation that has a heat loss lower than yours. The shared walls really save energy, it’s a good thing!  

Hot Water Fan,

Thank you for the post, yea I know the radiant floor is a bit much, but I can't stand rugs and carpet and winters are long and hard here, thus the radiant is going in.

As to cost, If I put the A/c ductless in the heat would be part of that, thus no cost difference, though with the floor unit handling the entire place, I am thinking of not putting it in, as I don't like A/C to begin with and just another item to service.

Thus the radiant floor is not to bad, the pipe was $300.00 for 1,000 ft and then the misc items.

I am only doing 2 zones so the manifold is also not bad. Its the boiler that has me in a quandary as to what to do. My last place and next place which is on hold till cost come down a bit, will have direct fire furnace for domestic hot water and radiant floors. This place I am trying not to add another utility to the requirements.

My Heat loss is off I am guessing a bit different than yours as I am a end unit so fully exposed except one side, the front faces west, the back east and the open side faces south, I am on top of a hill, pretty much highest point in the area is only 40ft higher and a mile away, the electric wind mills out my windows to the south also show a constant wind in the area.

So I am moving forward have a suggestion for electric boiler...

UT65

Jamie Hall said:

I completely agree with @Hot_water_fan on this one. You will be best served with a heat pump, assuming that whoever does the sizing and installation knows what they are doing.

Heat pump is not an option guys, 2nd floor pipe already in and the first floor I am debating moving it up from below to top mount. Thus looking at the floor leveling.

All floors are getting insulated underneath.

So forget the heat pump and stay on point with the question please.

What boiler would you use for this type of system in the electric arena?

How would you handle the floor being off level by 2.5".

I was looking at putting down a layer of 1/4" Light weight wonder board, then lay the pipes in place with clips and then stack glued and screwed wonder board as sleepers and then gypcrete between.

Then laminated floor system on top.

Zman

I would use something like this for the boiler https://www.ecomfort.com/Electro-Industries-EB-MX-15/p68427.html. Modulating and outdoor reset are nice features.

Hot_water_fan

Why did you insulate under the second story floor? 

Also, if you’re going with a radiant flooring using electric resistance, why not skip the tubing? Install electric mats and never worry about leaks, manifolds, boilers, circulatory, expansion tanks, etc. 

Jamie Hall

This ^^^.

My apologies for suggesting a heat pump. I really thought you wanted advice, not endorsement.

@Hot_water_fan is right again, though. You will gain nothing in terms of efficiency, never mind control, with tubing and all that. Electric resistance mats will give you considerably finer control, if you desire that, and are more efficient that an electric boiler/pump/tubing combination, and have less maintenance than a boiler.

UT65

Hot_water_fan said:

Why did you insulate under the second story floor? 

Also, if you’re going with a radiant flooring using electric resistance, why not skip the tubing? Install electric mats and never worry about leaks, manifolds, boilers, circulatory, expansion tanks, etc. 

Insulated for Floor noise, if I don't rent the place out once I move in a few years I will keep it as my office and We do a lot of video conference calls and need high level noise reduction. Need very quite rooms and with no rugs or carpet you hear everything hit the floors without AFB, so not really insulation its acoustical fire batts.

I looked at doing the electric mats, was more concerned with the floor movement and the mats because, a few of my clients did the electric mat direction in older home/office like I have and had nothing but issues with the mats with the heavy floor movement, wished they went water. so based on that I have stayed in this direction.

Thanks Hot Water Fan

UT65

Jamie Hall said:

This ^^^.

My apologies for suggesting a heat pump. I really thought you wanted advice, not endorsement.

@Hot_water_fan is right again, though. You will gain nothing in terms of efficiency, never mind control, with tubing and all that. Electric resistance mats will give you considerably finer control, if you desire that, and are more efficient that an electric boiler/pump/tubing combination, and have less maintenance than a boiler.

Jamie, Everyone has their views and choices which is why opinions are asked for in Forums, I get why everyone is pushing towards Ductless Heat pumps, but Ductless Heat pumps don't get us the result wanted which is heated floors... Just heated rooms.

Though cost is always a factor on any project, its the end result that is important which is heated floor system. Electric Mats or cable on 600 sq/ft is way more costly to install than hot water pipe and except for the pipe in the flooring everything else is in the basement and simple to get at.

thank you

UT65

Zman said:

I would use something like this for the boiler https://www.ecomfort.com/Electro-Industries-EB-MX-15/p68427.html. Modulating and outdoor reset are nice features.

Thank you Zman for the link

Zman

I am not a huge fan of electric mats, although I do see some benefits in cost to install and simplicity.
The downside is that you are married to them once they are installed.

• To get full modulation, you would need a special controller with SCR. Otherwise, they will overheat your slab and waste energy.
  
• They are very easy to damage during install.
  
• With hydronic tubing, you can swap out the heat source down the road. This would allow an air to water heat pump (with outdoor unit), solar, gas, or whatever new technology heads your way.