Abstract: A holding tank receives waste water from a dishwasher or laundry machine having a rinse cycle and at least one wash cycle. A pump moves the waste water through a heat exchanger at the same time that the rinse cycle requires hot water from a hot water heater. The cold water feed for the hot water heater is also passed in countercurrent heat exchange relationship with the waste water to provide warmed or heated makeup water at the same time that hot water is being withdrawn therefrom. The cooled waste water from the heat exchanger may be collected in a tank and supplied to any one or more of several additional devices, such as a water cooled refrigerant compressor, a grease extraction ventilator having water contact means, a waste food grinder, etc. The ventilator and compressor may also be placed in series, while the cooling water heated in the compressor is recirculated to the heat exchanger.

Abstract: A method of producing multiple coil, multiple tube heat exchanger from circular tubes, in which alternating turns in each coil have a warmer liquid and other turns a cooler liquid, by coating the outside of each coil with a heat conductive mastic and winding the next coil against the mastic to force the mastic into spaces between adjoining tubes of the first coil, into spaces of adjoining tubes of the second coil and into spaces between opposed tubes of first and second coils. Mastic applied to outside of each coli or into grooves between turns as next coil wound. Double tubes of each coil preferably wound into grooves between turns of preceding coil. Second tube of each coil started across coil from first tube and continued at end of coil past first tube. Succeeding coils wound against mastic in same manner. Turns of first coil attached together, as by soldering, while first and last turns of succeeding coils similarly attached to adjacent turn of coil beneath.

Abstract: A method of supplying tempered makeup air to a room in conjunction with a grease extraction ventilator disposed above cooking equipment in the room and having removal means for removing grease and smoke particles and the like from air mixed with products of cooking, which includes removing heated air and the remaining products of cooking, after passage through the removal means, through a discharge duct; tempering fresh air in a heat exchanger and discharging the tempered fresh air into the room; passing incoming air to the discharge duct in a manner which automatically regulates the amount of exhaust and makeup air required to remove and replace the minimal amount of outside air to eliminate heat, odors, smoke, gases, grease and dirt as the cooking load changes; and causing incoming air, which is not passed to the discharge duct, to become a portion of the tempered air for discharge into said room.

Abstract: A series of tubes wound in spiral, spaced relation in pressure contact with the next inner tube or a central cylinder to form, between them, a spiral path for one liquid flowing upwardly in the space between the tubes, while another liquid flows downwardly in the tubes. The outermost tube may be enclosed by a sheath in pressure contact therewith, while several sets of tubes, separated by corresponding sheaths, may be utilized. The diameter of the tubes may be varied for the sets to compensate for the greater length of tubes at an outer position, so that an approximately equal time of travel from one end of the tubes to the opposite ends may be obtained. The spacing between the successive turns of the coils is preferably a distance corresponding to one half the diameter of the tubes.