From NachiWiki

Review your options, consider the pros and cons of different equipment and fuels, and compare installation and operating costs. Now get ready to improve your existing system, and it’s time to select a contractor. Here are some tips:

Look for a registered contractor

Your contractor will supply and install your equipment. Proper installation is essential for the safe, efficient and economical operation of your system. Electric equipment must be installed by a licensed electrician and all electrical work must be inspected.

Get estimates from several contractors.

Prices can vary significantly among contractors. Ask each firm for a written estimate covering the following items:

• The total cost and a listing of all necessary work including improvements to the existing system and the provision of combustion air if applicable
• Heat loss/gain analysis
• The size and seasonal efficiency of the unit, and sound ratings if applicable
• Responsibility of the contractor or homeowner for:
  • Obtaining permits and paying related fees
  • Removing and disposing of old equipment
  • Arranging for such work as installation of gas supply
  • Arranging necessary inspections
• A work schedule and completion date
• Guarantees, warranties and service contracts
• Terms of payment
• Evidence of an electrician’s licence as appropriate

Use costs (both installed and operating), work schedule, warranties and service as the basis for your decision. Ask the contractors you are considering for references, and follow up by contacting previous customers. Ask what they think about the contractor, fuel supplier and the options you are considering.

Choose the right equipment

In order to correctly size new heating and cooling equipment, your contractor must analyze how much heat is lost from your home in winter and gained in summer. Ask for this heat loss/gain analysis in writing, including the method used to perform the calculation. This calculation should take into consideration such factors as the size of the house, its level of insulation and the condition of windows and doors. If the heat loss and gain is significant and you haven’t already taken steps to increase the energy efficiency of the house, now is the time to do it.

Avoid the temptation to simply choose the same size equipment that already exists in your house without doing a heat loss/gain analysis. Your home has likely been altered over the years and the system might even have been the wrong size at the start. An oversized unit will usually operate below peak efficiency, and both oversized and undersized units can adversely affect the comfort of your home. Any installation involving combustion equipment should include steps to ensure that there will be an adequate supply of air for combustion and venting, and that other air exhausting equipment will not cause problems.

Changing Your Water Heater

Size is an important consideration when selecting new hot water equipment. A larger family is likely to use more hot water. A “downsized” household – for example, an older couple whose children have grown up and moved into their own homes – will no longer need a water heater meant to supply the needs of four or more people. By practicing water conservation – for example, by installing energy-efficient showerheads and aerators on taps and using cold water in your washing machine – you can substantially reduce your hot water usage.

Steps to installing a hot water tank

Contact your local fuel supplier or contractor and ask for the efficiency ratings of the models you are considering. When you have selected a unit just big enough to meet your household needs, your fuel supplier or contractor can arrange for a qualified serviceperson to install the water heater. If you have an electric hot water tank, wrap it in an insulating blanket. Make sure the blanket is certified for use on your heater and is properly installed. Insulate both the hot and cold water lines of the tank and consider installing a heat trap. Be careful not to insulate the pipes too close to the flue of a fossil-fueled tank. Ask your fuel supplier about any water heating cost-saving programs they offer. Some suppliers do some of the work at little or no cost to you.