Water Heating Dilemma

I have been doing a bit of research over the past few weeks on the most efficient method for heating both our radiant heating system and domestic hot water. This is not meant to be an exhaustive account of that research but I am conflicted as to the best option. In the end we will most likely pay an experienced HVAC contractor to design the most efficient system for our needs. Below is a basic account of the pros and cons of the various options I have looked into so far.

Gas On-Demand, Boiler or Storage

Pros

  • Very efficient
  • Lower cost to operate than electric

Cons

  • We want an all electric home to allow for zero-carbon conversion in the future
  • We want an all electric home to reduce utility hookup costs and delays from the gas company
  • The gas supply lines in Philly can be too weak to sufficiently supply some on demand units

Electric Tank

Pros

Water Heating Dilemma

Cons

  • Not very efficient
  • High operating cost
  • Must keep tank heated at all times

Electric On Demand or Boiler

Pros

  • Very efficient
  • Small space requirement

Cons

  • Capacity can be limited
  • High current capacity needed may be too much for normal 200 Amp service

Electric Heat Exchanger / Storage Heater Combo

Pros

New Mechanicals for 100K
  • Extremely efficient
  • Cools and dehumidifies the surrounding air

Cons

  • Space requirement for both tank and heat exchanger
  • The heat exchanger will be taking heat from the indoor air during the winter in order to heat the floor which, in turn heats the air again. Sound like a vicious cycle to anyone?

Solar Thermal System

Pros

  • Extremely efficient
  • Renewable and clean energy source reduces the size of PV system needed to achieve zero carbon in the future

Cons

  • Installation is cost prohibitive on our budget
  • A large storage tank is needed somewhere in the home
  • A backup heating source is still required

This is not meant to be a discouraging post. We will prevail but this is an example of the challenges of finding the most efficient and cost-effective system for our affordable, green homes. You hope that there are easy and straightforward answers out there that can be easily found but it is not always the case. I have calls out to a few people who are looking into the best solution but if anyone has any ideas grounded in reality, they would be much appreciated. As I said previously, we will most likely invest in a professionally designed system to ensure we have made the best choice from a development and long-term standpoint for the homeowner.

Link:

Marker Time – Indoor Air Quality (Ventilation)

American Council for an Energy-Efficient Economy – Water Heating 

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