Posts Tagged ‘hydronic system’

Radiant Slab Heating – Insulating Under the Slab

Thursday, February 23rd, 2012

Radiant Heating

In-Slab Systems

Radiant Heating has come to be known as perhaps the most comfortable type of heating available today (next to laying in the sun at least).  In-slab heating is a common option to consider for basements, slab floors, and garages.  While building codes do not necessarily call for it, there is no question that  insulation under the slab will positively impact the performance of any in-slab radiant heating system.  Here is what every contractor should know about insulation and in-slab heating.

Insulating Under the Slab

As was noted in our piece Radiant Heating:  In Slab Systems – What You Need to Know About In-Slab Systems, the first thing to keep in mind is “when heating a slab floor, the goal is to efficiently heat the slab and direct as much of that heat as possible into the living/working space above it – practically speaking  6-8 foot air space above the slab floor.”

The use of an insulation barrier under the  slab is a critical component that will result in much greater efficiencies for the heating system.

Without an insulating barrier, the slab will likely be resting on a bed of sand and/or gravel.  Even though sand is not considered to be a good thermal conductor, it is also not a good insulator.  It will allow heat to escape in a direction that is not in our target area – the 6-8 foot air space above the slab floor.

Insulation options: There are a few different options to provide an insulation barrier for a slab installation.  Three of them are discussed here.

Rigid foam sheets:  If the ground is leveled off well, a 1’ thick layer of blue foam is sometimes used as an insulation layer.  The cost of material is relatively inexpensive.  Because it is typically made of closed cell foam, this can also effectively serve as a vapor barrier, but would need to be taped or sealed somehow where pieces butt together in order not to compromise this functionality.  If working outdoors, care must be taken to hold the pieces in place prior to pouring the slab.  Pieces can be crushed or broken while being walked upon during the installation phase as well, sacrificing performance.  Lastly, while a 1” thick layer of foam will typically provide an R-5 insulation value, the foam itself will still allow some heat from radiant tubing in the slab to pass through it into the ground (i.e. – someplace other than our target area).

Spray foam:  This method has many risks with it.  The foam itself should be closed-cell foam.  If it is not closed cell, it will likely lose its insulation value over time.  Spray foam has no inherent vapor barrier capability.  This would need to be added perhaps through a plastic layer both below and above the foam.  Perhaps the most difficult aspect of using spray foam is the ability to maintain a consistent thickness and density prior to pouring.  For all of the above reasons, using spray foam as an insulation barrier under a slab is strongly discouraged.

Insulating Tarp or blanket:  An insulating tarp provides a built in vapor barrier above and below an insulating InsulTarp6layer of air (much like the bubble-pack used for shipping in packages).  The upper layer of the tarp also serves as a reflective layer to help to maximize the amount of heat being directed to the target area above the floor.  Insulating tarp is easy to work with.  It can simply be unrolled over the desired area.  It can be easily cut and taped down to adjacent pieces in only a few minutes.  It can be walked on by installers without worry to integrity or performance of the product.  It does not take up as much thickness as a rigid foam sheet and best of all, it provides superior insulation performance (typically in the R-6 to R-7 range).

Summary

While the per square foot cost of the insulating tarp may be more than that of rigid foam, it’s benefits during installation (quicker and easier) and its superior insulating performance and contribution to toward the increased efficiency of the radiant heating system provides a quick payback for both the installer and the homeowner.  Going back to the goal of our in-slab system – to efficiently heat the slab (and not the earth below it) and maximize the amount of heat being directed into the air space 6-8 feet directly above the slab – it is easy to see that the use of an insulating tarp makes sense in any in-slab radiant heating system.

Hydronic Control Panels – What You Should Expect to Find.

Monday, January 9th, 2012

Hydronic Control Panels
What should you expect to find in a control panel?

WHAT IS THE VALUE OF A HYDRONIC CONTROL PANEL?

The control panel is the heart of the hydronic system. It should include all components that are not only compatible with the rest of the equipment connected to the HVAC system but allow the system to provide optimal performance. It should be easy to install. It should include all mechanical and electrical connection points. It must provide equipment that protects both the system and the home in case of equipment malfunctions. It should provide for ease of serviceability during routine and emergency maintenance. As it is perhaps the most visible system component in a customer installation, it should also provide a clean and professional appearance.

When considering a hydronic control panel design, the following should be taken into consideration:

  • Functionality
  • Installation
  • Durability and Appearance
  • Serviceability

FUNCTIONALITY

By definition the control panel is the main system component where the hydronic system should be controlled or operated from. This means that it should include as many of the system control elements as possible as well as be the electrical center for all equipment attached to the hydronic system.
Standard elements that should be included in a control panel design include: feed water regulator and backflow preventer, expansion tank, air eliminator, zone valves, circulating pumps, pressure gauge, temperature measurement for supply and return with delta, system controls, master power switch, electrical wiring connection points, and fill and flush connections.

Visio-showroom panel labeled.vsd

Basic Elements of a Hydronic Control Panel

Other items that can be included:

  • Fittings for a variety of piping types
  • Strainer or Dirt Separator
  • 3-way or variable speed mixing
  • DHW Piping and controls
  • Heat Exchangers
  • Glycol Feeders

Integrated Control Options

  • Variable Speed Mixing
  • Setpoint Controls
  • Ice and Snow Melting
  • Ecô Energy Management System

Wiring Connection Terminations for:

  • All thermostats and sensors
  • Circulation pumps
  • Actuators
  • All heat pumps, boilers, air handlers, and any other active equipment being controlled in the HVAC system.

INSTALLATION

As all control panels are essentially customized to a specific installation, the contractor essentially has two choices:

Option 1 – Build it on-site:

  • Pre-design or design-on-the-fly
  • Specify and obtain components
  • Work in potentially unconditioned and uncontrolled environment
  • Incur travel & labor costs
  • Test system on site
  • Make any revisions to panel at on-site labor costs plus travel

There are a lot of variables in this equation. Even with experienced personnel, costs can be unpredictable and difficult to control.

Option 2 – Have it designed and fabricated off-site for easy and quick installation:

Using Eagle Mountain/Hydronic Systems this provides the following advantages:

  • Full Control panel is designed and reviewed ahead of time for physical layout, components, connectivity, wiring layout, and panel size – before any fabrication begins.
  • Panel is fabricated in a controlled environment at factory labor rates.
  • All electrical control connection points are brought to a single electrical box mounted on the panel.
  • Panel is tested before leaving the factory.
  • The only labor required on the job site is for mounting the panel and making the physical connections to the rest of the system.
  • Cost of the panel is known up-front. Installation costs are not only predictable and more easily controlled, they are also greatly reduced.

DURABILITY AND APPEARANCE

Panel Material
It is common to find control panels mounted on materials ranging from plywood to steel sheets. While these materials are readily available and may be relatively inexpensive, they are not ideal for hydronic systems. By their nature, hydronic systems involve water. Components can collect moisture on external surfaces that eventually can migrate to other components in the system. This moisture will eventually weaken and warp wood materials potentially compromising the structural integrity of the control panel. Similarly, steel sheets may be subject to corrosion that may also bring similar risks to the structural integrity of the overall control panel.

An ideal material for control panels is a high-density polyethylene (HDPE) board. This material provides adequate strength and stiffness to accommodate all the control panel components, is completely impervious to the effects of moisture, and also provides a professional appearance in the home or facility where the control panel is mounted.

Panel Mounting
Any prefabricated panel should come with a mounting system that allows for simple and quick wall-mounting by one or two people (depending on the size of the panel). Connection to the rest of the system should be simple and easily accomplished once the board is mounted. Remember, one of the primary purposes of the prefabricated hydronic control panel is to reduce on-site labor.

Copper and Brass Handling
During fabrication, the copper and brass components should not be touched by hand due to the salts on the skin, or exposed to environments that can produce oxidation. Fabrication should be done using gloves designed for handling copper and brass that eliminate the salts transfer.

Cleaning
The piping and fittings need to be cleaned of the flux material used during the assembly to prohibit accelerated corrosion of the copper. The copper may also have surface oxidation from the assembly process as well as salts from shipping and/or handling of the copper by hand. These salts will accelerate the oxidation producing discoloration and eventually corrosion of the copper and brass components in the system. The panel should be thoroughly cleaned and polished to prevent any corrosion of the components.

Following installation, the control panel is perhaps the most visible component to any hydronic-based HVAC system. In addition to the serviceability issues discussed above, the value of a clean and well organized control panel that will stand the test of time should serve any contractor well as a showpiece for the type of installation and work that potential customers can expect from them.

SERVICEABILITY

Next to the ease of installation, the most significant criteria in control panel design have to do with serviceability. As the system is mechanical in nature, over time there is a significant likelihood that maintenance of some sort will be required. Chances are, if a service call is required, the first place a technician will need to go is the control panel. A well-designed control panel allows for easy access to all of the system controls in a consistent manner and provides appropriate access to all components. This design should include removable actuators and sufficient valves and drains to isolate any component for service or easy replacement.

Another benefit inherent with pre-fabricated control panels is that the contractor will have access to a drawing of the control panel available to them to review in the event of a service call. Having this information available will help technicians with remote trouble-shooting and save money in service calls benefitting both the business and their customers.

SUMMARY

Together, all of the elements discussed above add up to the value that the hydronic control panel can bring to your business. Each of these elements is important to both the contractor and the end-user. The decisions made around the design and installation of the hydronic control panel can have both immediate and long-term impact to the system functionality as well as to the relationship between the contractor and the system owner. Care should be taken to consider future maintenance as well as potential changes to the system. Weight should be given to the desired optimal performance of the system when determining system components and layout. All electrical wiring and controls need to be taken into account when designing and evaluating control panel solutions. Eagle Mountain’s hydronic control panels provide a high-value solution to any hydronic-based HVAC system.

Can you use Geothermal with Baseboard Radiant Heating?

Tuesday, August 31st, 2010
Boug Mossbrook

Doug Mossbrook

Yes, it’s technically possible, but the answer is NO.

We had a customer write in saying “At my IGSHPA training the instructor told us that using geothermal with baseboard radiant absolutely could be done -because the plumbers used to always oversize the baseboard runs anyway -maxing them out per room -so the lower 120 degree water temp would work.  I would like to know what the engineers up your way say about this.”

The short answer is no, don’t use geothermal with baseboard heating or radiators.

The longer answer is yes, but with a few caveats that will be explained here.  Baseboard heaters use convection heating to heat a room. There are typically fins inside the heater called elements. These elements have a set resistance, which transfers heat energy from the hot water and dissipates it in the form of heat to the surrounding air.

Because the warm air is lighter than the cooler air, it rises out of the top of the heater and the cooler air closer to the floor is drawn in from the bottom to replace the displaced warm air. This is convection.  This cycle continues until the air surrounding your control center or thermostat reaches the specified temperature.

Convection

Convection

The typical operating temperature of water in a baseboard heating system is roughly 160 – 180 degrees fahrenheit.  This high temperature is critical to be as efficient as possible.

Convection does not work with low temperature water from a geothermal heat pump.

And as we all know, a geothermal system is a low temperature heat source, with a maximum output temperature of roughly 115 degrees.  With radiant floor heating or forced air, this water temperature is perfect to heat a room, and it helps keep the geo system as efficient as possible.

115 degree water is not hot enough to adequately dissipate heat for baseboard hydronic systems.  It will dissipate some heat through the fins simply because the water in the pipes is warmer than the room; however, to heat a room to 70 degrees will take a long time, require a lot of energy, and additional surface area (more radiators).

The technical answer whether or not baseboard radiant works with geothermal is yes; however the cost of additional radiators, piping, and reduced efficiency make the correct answer no.  Baseboard radiant is most efficient when incorporated with a boiler system.  A boiler radiant heating system is capable of much higher output temperatures than a geothermal system.

Process to change Geothermal from Heating to Cooling

Monday, June 7th, 2010
Jason Murphy

Jason Murphy

Geothermal systems provide both heating and cooling.

If you have a forced-air geothermal system using a water-to-air geothermal heat pump, simply change your thermostats from heating to cooling mode, and you are done. Forced-air geothermal systems are the easiest to change from heating to cooling mode.

Cooling with Hydronic Geothermal Heat Pumps

If you have a radiant heating system, your hydronic geothermal heat pump provides cooling via high-velocity or low-velocity air handlers.

Step 1: Locate your Hydronic Control Panel


If you have a hydronic system, the first step is to locate your hyrdonic control panel in the mechanical room.  You control panel will look like this:

Hydronic Control Panel

Hydronic Control Panel

Step 2: Determine if you have 1 or 2 Tekmar Controls


The device that tells your heat pump to make either hot or cold water is a Tekmar 152 two stage setpoint control.  Your control panel will either have one or two Tekmar controls.

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