![\"Bard](\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2011\/08\/Bard-5-ton-wall-mount-AC-unit.jpg\")
<\/a>The new ACs are five-ton wall-mount Bard units. \u00a0These are three phase and should be more than enough to keep the transmitters cool. \u00a0Here is how I arrived at that conclusion:<\/p>\n\n\n\n
- \n
- The entire building load when the main transmitter is running at full power, without the transmitter room air conditioning, is 60 KW.<\/li>\n\n\n\n
- All of the building loads except the transmitters go through a single-phase panel.<\/li>\n\n\n\n
- The load on the single phase panel is 10 KW, thus the transmitter load is 50 KW (this 10 KW is mostly the single phase AC units in the combiner room)<\/li>\n\n\n\n
- The TPO is 32 KW, therefore the transmitter is generating 18 KW of waste heat.<\/li>\n\n\n\n
- One watt-hour = 3.412 BTU of energy, thus<\/li>\n\n\n\n
- 18,000-watt-hours equals 61,416 BTUs<\/li>\n\n\n\n
- One ton = 12,000 BTU, thus<\/li>\n\n\n\n
- 61,416 BTU \u00f7 12,000 BTU = 5.118 tons<\/li>\n<\/ul>\n\n\n\n
That will take care of the main transmitter waste heat. \u00a0The HD transmitter generates another 4,000 watts of waste heat or 1.37 tons. \u00a0The combiner is in another room and doesn’t factor into the calculation. \u00a0The rest of the equipment is inconsequential, adding up to less than 100 watts.<\/p>\n\n\n\n
The solar gain is more difficult to calculate, as it is based on the building structure, the type of construction, and the heat gain (loss) through the walls and doors. \u00a0This building is concrete block, insulated, and has no windows. \u00a0It is unshaded, however, it is painted a light color. \u00a0All in all, the solar gain should be less than two tons on a hot day. \u00a0Therefore the total AC load should be 8.25 tons or less.<\/p>\n\n\n\n
![\"Bard](\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2011\/08\/Bard-5-ton-wall-mount-AC.jpg\")
<\/a>Bard 5 ton wall mount AC unit<\/figcaption><\/figure>\n\n\n\n All that is left now was to install the things. \u00a0Just pull up the truck and use a crane to lift them in place, except, no; that plan won’t work. \u00a0This is the transmitter site at the power plant and the 138 KV lines overhead precluded any lifting with a crane. \u00a0We instead had to build ramps and move things around on large-hand trucks. \u00a0One unit is installed on the rear of the building, the other on the front. \u00a0It required several days to make the ramps and four people to muscle the things into place.<\/p>\n\n\n\n
The bottom air intake holes needed to be cut out for the new units. \u00a0Cutting into the concrete block while the BE FM 35A was running proved to be another challenge. \u00a0We used several sheets of plastic, shop vacs, and extra air filters on the transmitters to keep the concrete dust out of the PA cavities and motor bearings.<\/p>\n\n\n\n
Plan B cooling consists of a 4,292 CFM Venturi fan mounted on the rear wall of the building. \u00a0The fan is controlled by a ceiling-mounted thermostat set to 95 degrees. \u00a0If the AC’s fail, the ceiling temperature will rise and the fan will turn on.<\/p>\n\n\n\n
![\"Transmitter](\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2011\/08\/venturi-fan.jpg\")
<\/a>Transmitter site emergency cooling fan<\/figcaption><\/figure>\n\n\n\n The room volume is about 3600 cubic feet, therefore this fan will change the room air about once every 60 seconds or so. It is not the best plan to move humid, potentially dirty outside air through a building, but it it keeps the station on the air while the main AC units are being repaired, then so be it.<\/p>\n\n\n\n
The entire system went on line last week and is working well.<\/p>\n","protected":false},"excerpt":{"rendered":"
It was a hot day, it was a cold day. The tube transmitter was running, the solid-state (HD-1) transmitter was off the air. The books show that the company has deep pockets, but the accountant has short arms. \u00a0And so it goes. \u00a0In a sordid, yet familiar tale of leaping three-quarters of the way across … Continue reading A tale of two air conditioners<\/span><\/a><\/p>\n","protected":false},"author":4,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[4],"tags":[215,160],"class_list":["post-3410","post","type-post","status-publish","format-standard","hentry","category-tech-stuff","tag-fm-transmitter-site","tag-hvac"],"_links":{"self":[{"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/posts\/3410","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/users\/4"}],"replies":[{"embeddable":true,"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/comments?post=3410"}],"version-history":[{"count":11,"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/posts\/3410\/revisions"}],"predecessor-version":[{"id":11758,"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/posts\/3410\/revisions\/11758"}],"wp:attachment":[{"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/media?parent=3410"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/categories?post=3410"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/tags?post=3410"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}