HPAC Magazine

Cooling Options For Hydronic Applications

August 2, 2014 | By MIKE BUTLER

Cooling in a hydronic heating environment suggests that the heating is already present. In the perfect total system design, heat is delivered from the floor and cooling from the ceiling or high wall. This approach also carries the potential to eliminate the need for ductwork. How do we handle cooling for these areas if hydronic cooling is not included in the design or in a retrofit situation?

When adding or replacing cooling to a house the buyer has many choices with an “A” coil split system. Each manufacturer offers a variety of models depending on the price paid and the efficiency of the machine – typically a good/better/best scenario with the latter costing the most money and delivering the highest efficiency or lowest operating cost. Another benefit to the higher efficiency air conditioner is a much quieter system.

Are there any other solutions? Yes, in fact there are other choices.

1. A fan coil system consists of a fan box/a coil box and a filter box. Mounted indoors, this is connected to a condensing unit outdoors. Ductwork and diffusers are the hook up to deliver the conditioned air to the various rooms. It is also referred to as a split air conditioning system.

2. Ductless systems were first introduced in the mid 1980s, to high-end, hot water heated houses where the only previous method of cooling had been a window fan or a window mounted air conditioner. The window mounts were relatively small in size (and capacity) due to window size constrictions. All window units were considered noisy, especially in bedrooms.

The significant difference with the ductless is the coil (evaporator) is located in the room being cooled – i.e. bedroom or living room. The humidity reduction is instantaneous. You can walk into a room at 85F, turn on the ductless system and instantly feel cool air within the room as well as immediate humidity removal. Within 10 to 15 minutes the room will feel very comfortable. The sound levels are also extremely low.

An added bonus to the ductless system is the low cost to operate the system compared to the conventional split air conditioner. The applications for ductless have grown from residential all-purpose, hot water heated sites to targeting individual rooms, such as a home office, a sunroom, or a third floor addition (that last one, impossible to get ductwork to).

One manufacturer offers a wall mounted version disguised as a mirror or integrated into a picture. For larger homes in downtown areas, where outdoor space is at a premium, the option could be to have multiple indoor units (up to eight) all attached to one outdoor unit. These new options are available in a ductless heat pump version.

3. A PTAC (Package Terminal Unit) heating cooling unit is a low cost alternative. It is a one-piece decorative air conditioner that fits into a room through the wall sleeve. It can be used in existing, renovation, or new construction applications, normally using one unit per room. These units are typically used in hotel and motel complexes, and also commonly found in apartment rentals and condo units. Vast improvements in system technology, energy efficiency, more accurate temperature control and much lower sound levels make this product a viable choice.

4. A high-pressure system is similar to the fan coil system in terms of equipment and offers good dehumidification. This system is easy to install and is primarily placed in the ceiling space or attic of a building using very small diameter plastic pipes with a high velocity fan system. The pipes run to each room from a central location and are hidden from view except for the diffuser. There is very little disruption to the living area and no need to redecorate after the installation.

5. Temporary Spot Coolers are a good solution for an emergency or temporary problem. They were originally designed for urgent cooling requirements for computer rooms or hospitals. They have since developed into a variety of uses including kitchens, living rooms / bedrooms (senior apartments), fixed window rooms, and home offices. One was even spotted in Japan outside the entrance to a major hotel, to keep their customers cool while they lined up waiting for taxis.

Current Environment

Government regulations are getting increasingly tougher with higher and higher energy efficiency goals and third party verification of equipment performance. The end result is more technically advanced products that require better educated and skilled service mechanics.

Consumers are more informed and demanding. They want explicit details of what equipment you are supplying and why you chose it. They are Internet savvy and will likely check your information for accuracy before they buy. As a business professional you should always be aware of all current trends to make the best recommendations for each job. You must give your customer all the proper options for their application to keep the competition honest and secure the business. <>

Mike Butler has over 40 years of sales and marketing experience in the HVAC industry with various manufacturers. He is currently with Airon Group of Companies where he is responsible for sales and application solutions.


Residential cooling refers to any space used for a family dwelling — one that requires human comfort only, and not professional accoutrements. For example, a house used as a doctor’s office is considered commercial use.

Commercial cooling refers to any non-residential cooling environment. Some conditions to be considered are (i) building type, (ii) materials used, like brick, stone, wood siding, aluminum/steel panels or concrete panels, (iii) various types of insulation in walls and ceilings and the insulation’s R values, (iv) exposure to sun and wind, and sun blockage from trees or other buildings, (v) amount of glass used in square feet, type of glass (single, double, triple plate or thermo pane) and any special features, such as reflective ability or E-type glass.


Contractors need to fully consider the customers’ expectations. Completely understanding customers’ requirements involves taking detailed notes and leaving specific instructions for the installation department as to the outdoor unit location, drain considerations, type of thermostat required, etc. Contractors should also fully identify all potential problems and advise installers about factors like thermostat location, condensate pump required, plenum changes to fit A-coil, yard access for outdoor unit, etc.

Relevant considerations for notes/instructions:

• Multiple systems: with hydronic systems, some people want dehumidification more than cooling, which can be satisfied via multiple ductless units in key rooms

• Confirm adequate electrical supply before–not during–installation

• Determine exact path of drain for condensate from the A-coil, and whether a pump is required (if so, build it into the price otherwise in order to avoid extras or, worse, absorbing the cost)

• Remember: there is only one thermostat per system, so instead of simply remounting the new one in the old location, look around to see if there is a better location that would give a better overall comfort level

• Building codes require specific amounts of fresh air—find out if fresh air needs to be added to the contract due to negative pressure in the building (and advise the customer, as this will affect the cost)

• Access restrictions: never take access for granted—always survey the area before placing
equipment in the mechanical room and placing outdoor units on ground or roof

• Do not let the customer determine equipment location: the after-the-fact customer will deny choosing the location and blame the contractor for being the expert and not advising.



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