Custom Modification of Heat Pump Installation

Somewhere in King County, 25 September 2008: --

This is the tale of an old retired Mechanical Engineer, who was not completely happy with the installation of his new Heat Pump. The problem wasn't with the Heat Pump itself, but rather the way in which it was integrated with the existing oil furnace -- or should I say, NOT integrated with said furnace.

The story starts with the initial requirement that the Heat Pump (a very sophisticated, two-stage hummer) be installed to be compatible with the existing (50 year old) oil-burning furnace, exploiting the capabilities of that furnace's three-speed blower. The three-speed blower is an update that Grumpy had installed a few years back -- the original blower was a single speed. To make matters even worse, the schematics for the new three-speed blower motor were not available and the schematics on the blower door of the furnace were virtually unreadable.

To make matters very interesting, if not really worse, the problem of hooking up this three-speed blower with the fancy Heat Pump and even fancier electronic thermostat interface adapter unit, involved electrical wiring and relay logic. Now if it was just plain logic, Grumpy could have called in his philosophically-inclined logical Grandson Lief and the problem would have been solved in a trice. But, knowing he was on his own, Grumpy put his mechanically-inclined mind to work and after several trying hours and innumerable cups of the Grand Mother's coffee, he determined that he had found a solution. (Note: "a solution", not "the solution"; it is a well-known fact that if you ask two Mechanical Engineers to solve a problem, they will come up with at least four "known solutions", none of which either of them will give you a guarantee in writing that any of them will work.)

Grumpy took his "solution" to that famous local company known as BIC, Inc. Now this company's claim to fame is that they can fabricate anything made of electrical wires, complete with connectors on each end of each wire and loomed together to form an apparently fully-engineered end product. Typically, these products are custom-tailored to meet customer requirements. The company has customers who are lined up in a considerable backlog for these custom products.

After a hard negotiating session with the Chief Engineer of BIC, Inc., as well as its hard-nosed CFO, Grumpy was able to obtain a "promise to perform" in fabricating the product which is called, "Relay Logic Module" (RLM, for short). This module consists of four relays, one of which is a double-pole, double throw type. The function of the RLM will be to interface between the electronic thermostat interface unit and the oil-furnace with its three-speed blower, and to allow exploitation by the Heat Pump of the full capabilities of the three-speed blower.

The finished product is pictured here; it measures about 3"wide by 6.5" long and stands 2" high. This is well within Grumpy's stated maximum dimensions of 4.5" by 7.5" long and 2.75 " high. As soon as it is hooked up and the system is checked out, the Grand Mother and Grumpy will be able to enjoy the full capabilities of their sophisticated new two-stage Heat Pump with its ultra fancy automatic thermostat and the full capabilities of the three-speed blower!

Ah! Automatic heat in the Fall, Winter and Spring, and automatic cooling when ever necessary or desired!! No more of Grumpy's previous annual edict of "First of October, furnace ON; First of May, furnace OFF".

Don't the readers think Grumpy deserves a Lemon Meringue Pie for this? Huh?!

Vote here, vote now: (click on "Comments" and say "YES"!!)

Vote often.