maybe. how is the tubing installed?

We have 1/2 diameter pex tubing in loops that are less than 300 feet in length. Those loops are placed on a sunboard made of 15/16" thick furniture grade plywood; the tubing loops consist of standard 1/2" Pex tubing that are on grooves 7.5 inches apart. The 15/16" thick plywood is covered with a .007 thick aluminum layer.

that's pretty high for wood floors, I wouldn't go any higher for sure. If you need to go that high, a reset mixing device would be pretty important.

Your solar integration is a bit more involved than just putting a boiler in line though. I don't know if your electric tank does domestic, but if so you should be separated, and you would not want residual heat from the oil boiler making its way to your solar tank and reducing your solar fraction.

We have no problems when the outside temperature is 35 F or above. The real problem is when the outside temperature is below 30 F and windy. The question would be if the temperature outside feels below 0 F. Would a temperature 0f 140 F going through the pex tubing do any damage to laminated wood floor?

In order to spend less oil we are planning to have hot water coming from the solar tank to go to the boiler and have more heat added to it and go to the 50 gallons electric tank heater to be use as back up during extremely low temperatures. Since after solar equipment and labor, solar heat is free, as you say I really wish to use solar heat as much as possible. For domestic water we have a Seisco RA 32 KW Electric Tankless Water Heater as a back up to the hot solar water tank; it is activated to add heat to the solar heated water if it does not have enough heat.

Now Another question: We have six rooms upstairs and the electric tank is in the lower floor; most of the time, we don't need the lower floor to be warm unless we have visitors sleeping over. I am considering the possibility of buying either a General Electric 50 gallons tank with heat pump technology or an 80 gallons Stiebel Eltron Accelera 300 Heat Pump Water Heater; the only problem is that S. Eltron is twice as expensive than the GE heat pump water heater. I know that heat pump technology is useless when the room temperature is too low. Now if I decide to put a Heat Star 1500 infrared heater with a thermostat few feet away to make sure that the temperature in the room is never less than 70 F. If the solar heat is not enough, could that electric heat pump water tank generate enough hot water to heat six rooms in the upper level of the house?

your setup is incorrect and will reduce your ability to collect solar by allowing residual heat from the oil boiler to potentially raise the solar tank's temperature when the solar tank is not hot enough to meet demands. you really want some intelligence deciding when to bring the solar in and when to keep the oil heat out of the solar tank.

your heat pump water heater draws heat from the room. You cannot use it effectively for space heating. You would basically be heating with straight electricity (the infrared heater) or oil (lost heat from the upper floors) and reducing your efficiency further by the energy draw of the heat pump.

140 *shouldn't* damage the floors but if they are poor quality it might. obviously you don't want to use it all the time though and again a reset mixing device is the answer.

this is not a case of just adding a boiler and whistling a merry tune. Not unless you enjoy wasting your money on the solar end.

It is something very difficult, like serving two different masters; on the one hand is physical comfort while on the other hand is to minimize as much as possible the possibility of having wasted money on solar heat. The most important thing is that two years ago I had to pay for oil almost monthly from September to April; still we have a tank of oil that is almost full since two years ago even though we have to occasionally turn on the oil boiler to heat the house radiators which need water over 170 F when the solar/ electric heat is not enough. However, the price of electricity has been going too high while the price for oil is more stable now. At this time, the real challenge is to lower even more my monthly electric bill.

you can integrate a boiler, I'm just saying, it's not a simple as piping it inline and running it, which would hurt the solar fraction. you need some control on this.

that said, if your system requires 170 degree water to heat appropriately, then you might want to address that first. additional emitters would be a big help, more radiator or baseboard.