New Mechanicals for 100K

We have been trying to nail down the mechanical systems to spec out in the house for some time now. We are getting very close, especially after the recommendations from the energy modeling. Our mechanical contractor is having health issues and had to bow out of the project so these may be subject to change based on recommendations of the ultimate mechanical contractor that comes in. We are also entertaining the option of just installing everything ourselves with the cooperation of a good plumber.

Solar Thermal System

SCHUCO Slim Line II-80 Solar Thermal Package – Currently we are looking at this two panel packaged system that comes complete with the storage tank with integrated heat exchanger. The price is not to bad at about $4K list from what I can find, but the important thing is that the entire package is certified by the Solar Rating and Certification Corporation (SRCC). This will qualify us for $2,000 federal tax credit that is available for solar thermal installs. The tax credit is for 30% of the installed cost of a qualified solar thermal system, so after labor it should be easy for us to qualify for the full amount.

New Mechanicals for 100K

Lastly, installing this system will take care of a majority of our hot water heating demand and will increase the overall efficiency of the house to the level that will allow us to take advantage of the full $2K federal tax credits for builders who build a home that achieves 50% energy savings for heating and cooling compared to code homes. These two tax credits will hopefully cover the majority of the solar thermal system and allow us to hit our energy efficiency targets on our budget.

Hot Water Gas Boiler

Munchkin T50-R2 Boiler – We were recommended a number of high-efficiency boilers but are leaning towards the Munchkin brand at the moment for the following reasons:

Marker Time – Indoor Air Quality (Ventilation)
  1. 95.1% efficient (AFUE %)
  2. Affordable – Around $2,500 list where most others are above $3K
  3. Modulates for improved efficiency
  4. Great brand name

The above two items in our mechanical system will very efficiently handle both our domestic hot water needs as well as our radiant heating needs. The solar storage tank will supply the domestic HW only and use the solar thermal panels as a primary heat source and the boiler as the secondary heat source. The boiler will be connected to a closed loop radiant system as well as the solar storage tank.

Radiant Heat in Slab on Grade Foundation

We will be installing PEX tubing ourselves for the radiant system prior to pouring the concrete slab that will remain unfinished. We will purchase the rest of the components needed as a pre-assembled package from any number of vendors that offer them. Not much more to say about that.

Free Radiant Cooling – A Closer Look

Energy Recovery Ventilator (ERV)

It looks like we will be going with the Ultimate Air RecoupAerator Whole House ERV Unit (Model 200 DX). This model has a couple of advantages over others we’ve looked at:

  1. As an ERV, it will maintain humidity as well as temperature, where an HRV only deals with temp
  2. Very low power consumption and quiet operation
  3. MERV 12 filter comes standard helping with LEED points and keeping the indoor air cleaner
  4. 95% efficient
  5. Variable speed controlled by time settings or programmable thermostat
  6. EconoCool feature allows cooler night air to be brought in directly during cool summer nights to cool the home without traditional air conditioning.

This last point is obviously a big one for us. Our concrete slab should absorb a lot of heat during the day and then release it at night as the ERV cools the home with fresh outdoor air.

Options

There are a few options or variables that could cause this list to change. For one, there are quite a number of ways we could configure the combination of radiant, solar thermal and domestic hot water. I may go through a couple other possible options in the next few days. Besides the ERV, we may install some type of dehumidifier in the home to ensure that the summer months are comfortable. I am actually considering purchasing a room dehumidifier and running it in our poorly insulated loft apartment to see how it works. We will most likely have to make a decision prior to gaining any useful data from this experiment, but I think it will be valuable none the less.