Dec 19, 2004, 11:53 AM
Post #2 of 23
I would think twice before opting for a hot water radiant heating system in Mexico. They are not as simple as they appear to be. It always seems strange to me that laymen with no construction experience will look at a project and conclude, “That’s simple, anyone can do it.” Well anyone can’t do it usually. There is a lot of math and science involved in the building industry. I have never heard of anyone providing a cost per square foot for one of these systems, there are too many variables.
I worked for 48 years in the pipe trades. I went through a normal five-year apprenticeship including on the job experience, and classroom work for which college credit was earned. I then worked as a journeyman, foreman, general foreman, project manager, etc. I have been licensed as a plumber, pipe fitter, and refrigeration technician.
In most jurisdictions in The US it is illegal for anyone without a license to work for remuneration as a plumber, electrician, etc., exceptions are made for a person working on their own home provided all codes are complied with. The licenses are issued to a tradesman personally after testing and proving qualifications, and must be renewed annually like a drivers license. I also owned my own control company. I am qualified to give some advice on heating systems. I have installed many of them.
If you plan to use in floor grids, they can be a specialized type of plastic, but they are usually cooper tubing. The joints in the copper tubing should be either silver soldered (really a form of brazing) the solder contains a high percentage of silver and is fairly expensive, or at least they should be soldered with 95/5 solder (95% tin, 5% antimony), that is the type of solder used in refrigeration systems. Care must be taken to assure that the copper tubes to not contact a dissimilar metal, such as the rebar in the floor, if they do, a condition called electrolysis will be present. Electrolysis will destroy the copper tubing.
I think you would be hard pressed to find a tradesman with the education and experience to do the installation in Mexico. Most of the “plumbers” and “electricians” I have talked to in Mexico are simply unqualified. Most of them are simply “handymen”, not qualified tradesmen. I believe the lack of enforced building codes is the reason. There are exceptions of course. I have spoken to a few that were highly qualified, that is not the norm here though
A separate, dedicated water heater will be required, a domestic (household) water heater is completely inadequate, and it will never produce the heat required. In this climate, you could probably set the heater to produce 150º F or 160º F, in Alaska we used to set them to produce 190º F in order to heat the building adequately.
A pump to circulate the hot water will run every time a thermostat in any zone calls for heat. You could get by with one zone for the whole house, but that would be wasteful. You would probably need at a minimum two zones for a two-story house. More zones than that are recommended for economy and comfort. Installing thermostats will require more wiring in the house of course. There will need to be elaborate controls, to start the pump, and open the valve for the zone or zones calling for heat. The controls are low voltage, so there will need to be a transformer to drop the voltage.
The heaters are heavy; the heat exchangers in them are made of cast iron. The heater, (usually called boilers although that is a misnomer), must be installed inside a room with ventilation and exhaust to outside air so the boiler will have adequate combustion air, and to keep all the electrical controls dry. It’s also so you won’t die of carbon monoxide poisoning.
These are what are called a “closed system”, that is a system where the water re-circulates and that is not directly connected to the domestic water supply. There is what amounts to check valves to prevent any water from the heating system to back flow in to the household water supply and contaminate it. They use low-pressure water; we usually had to install a pressure-reducing valve to drop the pressure to 15 PSI. Here you would usually have a hard time boosting the pressure to 15 PSI. Since a column of water one foot high produces .433 PSI, the outlet from your tinaco would need to be located 34.56 feet above the inlet of your heater, not the ground level, to consistently produce at least 15 PSI at the heater.
In my own opinion, unless a home was designed for this type of heating before it was built, it is not a practicable option here. The cost of electricity and propane must be considered too.
Here is a link to another reply I made to a post a couple of years ago to a person that was considering adding this type of heating to an apartment, using baseboard diffusers instead of in floor grids.
I don’t mean to be discouraging, but if you are considering this type of a heating system, there are many things to consider.
I don’t post to this forum often, it seems there are a lot of well meaning but technologically challenged people that will always post a reply that “My “plumber” says that doesn’t matter.” Everything in this post does matter.
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