hydronic radiant heating for full gut renovation

Jeff4radiant

I am doing a full gut reno including basement slab on 1900 house just outside of NYC in New Jersey(zone 4). It is a dupex with each unit getting two floors. I will be living in the 1st unit which includes the basement and first floor and is around 2200SF. After the sewer lines are fixed, I will add the 2" of foam and installing the rebar and pex. I will be hiring a crew to pour the new slab. After I will be adding insulation and casement windows to the basement . Around half of the 1000SF will be open entertainment area while the other half will house the guest room, office, mechanical room, w/d and full bath. I believe the entertainment area will be one zone with the other half being the second zone. I could make the guest room its own zone since we won't always have people over so I figure 2 or 3 zones for the basement. Basement height will be just over 7'.

On the 1st floor, we are creating the master suite and another bedroom and full bath. (2 Full baths on this floor) Rooms with bathrooms and hallway will take up half of the 1st floor. The other half will be open concept kitchen, living room with fireplace, dining, etc. We will be insulating inside and outside, creating an air tight envelope(tyvac or similar, rockwool, and then siding). Again we will be getting casement windows and will have the southern facing windows treated. We are trying to follow passive house guidelines but not looking for passive house certification. We plan to install duc less mini-splits (Mitsubishi) only on the 1st floor with zones in each bedroom and one for the great room. This will keep us cool and give us a heat backup. 1st floor height is 9'.We are also planning on using an ERV to get fresh air to both floors since we will be air tight. I can provide the layout the architect has so far if it will help.

I initially found this site looking for review for radiantec. I almost got them to design a system but with all of the bad reviews I held off. Here is what I am thinking. I would like a hydronic system for 2200 SF over 2 floors. The second unit is above mine and will require heating also but I just need to figure out my unit for now. I would like to use a hot water tank for both DHW and for heating. We currently have a NG boiler and hot water tank but with the insulation I think just a hot water tank will be enough. I was told a combi boiler would not supply the endless hot water I wanted for 3 tubs and kitchen etc., plus it would have problems with the heating side, so a hot water tank is fine. I also looked at a heat pump water heater but if that makes it too complicated, I can go with a regular electric water heater. I will have PV panels now or sometime in the future, depending on how much this round costs me. The mechanical room is in the middle on one side of the basement so I shouldn't any problems with run lengths. On the 1st floor I could do warmboard or something similar but their prices seem pretty crazy for just plywood with pipe grooves.

Sorry for the large dump but I hoped it would ease questions later. I am willing to pay for a design expert or build it here, again I am flexible.

Thanks,,
Jeff

Ironman

The first step is proper design and a load calculation. Without that, your just shooting in the wind.

Your wise not to use radiantwreck. I've seen too many of their jobs.

A water heater is not the proper tool for the job and probably could not supply enough btus for the size of your house - especially an electric one. They only produce 15,300 btus. And unless you get one with a separate coil for space heating, you'd have a legionella breeding machine. You're gonna need a properly sized mod/con boiler to get the best results.

Also be aware that in an older home, a radiant floor may not produce sufficient heat in colder weather and some form of supplement heat may be necessary.

Again, proper design is your foundation and first step before planning anything else.

Steven Minich and Rich McGraff are a couple of good ones and they frequent this site.

psb75

Warmboard is NOT just plywood with grooves. It is subfloor plus insulation plus aluminum for heat transfer and spread.

BillyO

Warmboard an excellent product and super easy install. Great Stuff, Really

TAG

Since you are doing a new slab -- can you get more than 7' -- or would you need to under pin the foundation? 7' is code ... but even 7.5 makes a huge difference.

My current project has a lot of Warmboard subfloor -- it is expensive .. but it makes for a very sold floor and it works.

Jeff4radiant

@Ironman I am basically putting a sweater on my house (Matt Risinger saying). By the time I am done the walls will have a R value of 30+ and the windows will have a u value around .20. Also I am making it air tight so this will be far better than new house code. I will see if I can get some calculations pulled together and posted over the next week or so.

@psb75 agreed it is more than I stated but that price tag is something else, to say the least.

@TAG the local code won't let me dig down. But it is actually 88" so closer to 7.5' than 7'.

pecmsg

What are your plans for outside air?

Jamie Hall

pecmsg said:

What are your plans for outside air?

Amen, brother. You really should have some means of controlling outside air in and out -- and preferably using a heat recovery ventilator. I like two air changes per hour minimum. Otherwise, your indoor air quality will be... pretty poor.

Jeff4radiant

@pecmsg I am looking into Zehnder models but very interested in cerv2.
I don't plan to put AC in the basement and wonder if the cerv2 would be better since it handles humidity too.

pecmsg

Jeff4radiant said:

@pecmsg I am looking into Zehnder models but very interested in cerv2.
I don't plan to put AC in the basement and wonder if the cerv2 would be better since it handles humidity too.

How does it Handle Humidity?

TAG

Why no AC .... conditioning in the basement ?

I have been doing my homes with spray foam since the early 90's -- they need humidity control.

The need for air changes depends on the house and how many people ... I moved from the HRV/ERV school to using a simple intake to a whole house dehumidifier with controller to the HVAC system. Houses leak ... even spray foam. With a small fan pressurizing the house -- I feel this is better in a radon are as well. North Jersey is in the zone.

Smaller house w/ more people needs more. Most places want makeup air for stove hoods now .... that can be huge