What should customers know about EFH and nailed hardwood?
With this application, note the manufacturer's requirements of the wood:
Nail distance?
Glue down? Nail down? Both?
The manufacturer's product that is approved for installation over embedded floor heat:
Maximum floor temperature allowed?
Minimum and maximum Relative Humidity. Humidity levels are very important in the winter and the summer. The customer will probably need to provide humidification in the winter and dehumidification in the summer to comply with the warranty of the manufacturer. Cupping, gapping, checking, etc. are not simply a result of having EFH installed (even though everyone will probably blame the EFH), the culprit is usually incorrect indoor Relative Humidity levels. This information is very important for the customer to obtain for their product. Not really important for us, just a good reminder for the customer while we are talking with them.
Maximum floor temperature daily differential*
*It is a good idea to ask if the manufacturer has a maximum daily temperature swing specification. This would be the maximum difference in the temperature of the floor per day.
Some flooring manufacturers specify that the temperature of a floor should be adjusted in small amounts, especially when the floor is turned on for the 1st time each year and then shut down for the summer. As an example, some companies will state that the floor temperature be adjusted 2 degrees per day, over the necessary number of days, up to their recommended max temperature. The same process may need to be followed when turning the system off for the summer.
If a flooring manufacturer specifies that the daily operating temperature differential is a maximum of 2 degrees (or similar) per day, that means that the thermostat's default comfort and economy settings may not comply with the requirements set forth by the flooring manufacturer. If the flooring manufacturer specifies a tight daily temperature range, it may be better to sell the customer a non-programmable thermostat, set to floor mode, to maintain a constant required temperature 24/7. This constant temperature may help keep the floor from expanding and contracting on a daily basis.
Some flooring manufacturers may not have this requirement, but it is a good question to ask.