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Finally finished that forced air furnace installation.
For either person who might have followed my progress through the first two installments, here's the third, (and thankfully final) item in the series. It works! :-) ************ Webasto Blue Heat, Part III "Let There be Heat!" (We've been reporting on a new do-it-yourself heater installation kit by Webasto. The project has involved replacing an existing, 20-year old diesel furnace on our Sundowner Tug, "Indulgence". Previous issues have detailed the planning process preceding the installation, removing the old heater, mounting the new Webasto Air Top 5000 on its bracket, and configuring the exhaust system.) I was slightly discouraged with the amount of time involved with getting the heater mounted, swapping out the through hull, and creating the exhaust system. It seemed questionable whether we would have our new diesel furnace installed before spring. The fuel system, wiring, and ducting yet remained, and experience with other projects has shown that fuel and wiring issues can be more complex and time consuming. Any number of false started, trial and error, mistaken processes seemed likely, but I was about to discover two of the greatest benefits of Webasto's do-it-yourself kit. Although the fuel and wiring systems would be the easiest portions of the job to foul up, Webasto's kit has simplified the connections. Even a stumblebum such as I can complete the more technically complex portions of the installation with only basic mechanical skills and simple tools. Fuel System: The do-it-yourself kit includes a new dip tube and fitting that is intended to be installed on the top of the fuel tank. Webasto warns against installing a "T" fitting in a fuel line to a main engine or generator. Instructions state that the Air Top 5000 may not function reliably without a dedicated fuel source. Following the instructions, exactly, would have been difficult aboard "Indulgence," as there is no practical access to the top of the fuel tank- especially with sufficient vertical clearance to insert a 30-inch dip tube. Disassembling the boat to reach the top of the tank would have been absurd. The old furnace had worked for twenty years with a "T" fitting, but I wanted to set up a system that would comply with Webasto's requirement for a dedicated fuel source. The solution, while somewhat unique to "Indulgence", proved to be easily apparent after only a few minutes of consideration. Our boat loads heavy on the starboard side. There are several hundred pounds of batteries and about 200 pounds of tools and spares that stow most logically on the starboard side of the design. The helm and the majority of cabin fixtures are to starboard, and as a result "Indulgence" can list just slightly to starboard without some correction. As we have a single engine and two fuel tanks, we set the valves on a fuel manifold to draw down the starboard tank faster than the port. Either tank will supply more than a sufficient volume of fuel to the engine underway. By adopting a policy of shutting off the port tank at the fuel manifold before running the Webasto, we can comply with the caution against sharing a fuel line with another system. The "T" fitting is between the port tank and the fuel manifold, so when the manifold valve is closed the port tank is entirely dedicated to the Air Top 5000. The fuel management policy satisfies the operational requirement of the Webasto furnace without requiring a major refit. As with several aspects of our specific "retrofit", this adaptation may not be practical on all vessels. Boaters with better access to their fuel tanks would be well advised to install the Webasto fitting, a process that the directions indicate should be simple and straightforward. Webasto furnishes a modular fuel pump assembly with the Air Top 5000. The 12-volt pump and a filter are mounted in a metal case, with "in" and "out" compression fittings. The pump makes a pulsing noise when operating, and rubber sound isolators are recommended when attaching the pump to a bulkhead or floorboard. One of the few disappointments with the do-it-yourself kit was that many of the small parts were sacked up willy-nilly and not always separated by system. Webasto furnished four mounting "legs" for the fuel pump, but I failed to find them (or to realize what they were), until I had fashioned a mounting plate from a bit of scrap sheet metal stock. The fuel pump can be mounted on a horizontal surface, and may be mounted vertically providing the "out" fitting is at the top of the case. Mounting the pump upside down could create an opportunity for air bubbles to form in the fuel line and interrupt the supply of fuel to the furnace. We mounted the fuel pump horizontally, behind the engine room ladder and less than a foot from the "T" fitting. Rigging the fuel line was extremely easy. Our old heater had a plastic fuel line, which has to rank among the more unsafe practices in an engine room. A plastic line could burn through in a matter of seconds and literally pour diesel into the flames. The ABYC compliant fuel line for the Webasto is a length of copper tubing. Connections were made with compression fittings or some specialized rubber hoses and clamps supplied by Webasto. I added an optional, additional filter jut beyond the "out" port of the fuel pump case, routed the fuel line under and behind some bracing structures where it would be protected from careless tool use in the engine room, and connected it to the fitting on the Air Top 5000. It would have been an auspicious day to buy a lottery ticket; when I opened the valve that connected the Webasto pump to the fuel system, all the connections on the non-pressurized side of the pump proved to be properly done. I wouldn't know about the pressurized side of the system until I actually activated the pump and ran the furnace, and that would need to wait until several additional steps were completed. Wiring: The Webasto kit makes wiring the Air Top 5000 extremely simple. The instructions could have been slightly more explicit regarding the connection of the small, fuel pump control circuit plug on the wiring harness. All wiring connections to the furnace proper are located under a removable plastic cover. The main harness connection is obvious, but the smaller receptacle for the pump control circuit is concealed under a removable rubber plug. Once the fuel pump control circuit mystery was resolved, there were only five other very simple connections to accomplish. The Webasto wiring harness separates into two branches just beyond the furnace. One branch is routed to the Webasto control module, and simply plugs in to connect. We located the control switch near the helm. The do-it-yourself kit does not include a thermostat, but rather a rotary switch with an infinite number of positions between "Low" and "high". The wiring harness does have some "extra" wires that could be connected to an optional thermostat, but they aren't needed for a complete and properly functioning installation. The other branch of the main wiring harness is routed to the "house" battery terminals. The brown wire connects to the negative side of the battery, and the red wire connects to the positive. The red wire has an inline fuse holder, and Webasto includes the fuse with the kit. The power supply circuit to the fuel pump connects to a pair of leads that protrude from the bottom of the Air Top 5000, literally routed through the combustion air intake port. Webasto ships the unit with some tiny "alligator" clips on the end of the wires protruding from the furnace, and the female end of a specialized plastic fitting on the power supply wire connected to the fuel pump. The connection seemed tenuous, to me, and I also had roughly six feet of excess cable between the furnace and the fuel pump. I cut away the extra length of fuel pump wire, cut off the alligator clips, and used butt connectors instead. Ductwork: There are four types of intake and exhaust considerations required for a forced air diesel furnace: combustion air intake, combustion exhaust gas removal, heat duct outflow, and cold air return. The exhaust system had been installed just after mounting the furnace on its bracket. (See last month's issue) Combustion air can be introduced via a through hull fitting, or simply drawn in from the bilge. I had hoped to bring in outside air, but couldn't clear the 18" radius that Webasto recommends between the exhaust through hull and a combustion air intake through hull. Moving the combustion air intake 18" forward would put it in a location closer to our bow wake than I thought advisable. Moving the air intake through hull 18" aft of the exhaust fitting would put it in an inaccessible location behind the port fuel tank. We finally opted to take combustion air from the bilge, and installed a special section of short, double walled hose that Webasto supplied for that purpose. The double wall hose construction is intended to reduce airflow noises. The cold air return was an interesting retrofit. We used a section of the cold air return from our old system, which proved to use a different diameter of duct hose than the Webasto. Sure Marine supplied a specialized "Y" that made the adaptation possible, but would not have been required in a from-scratch installation. The "Y" was one of only a few items needed to complete the installation that weren't included in the kit, and all the rest were extremely incidental or were specialty tools, (such as hole saws), that many people would already own. Many boat-heating experts suggest a cold air return system that provides a 70% "recycling" of previously heated cabin air and introduces 30% of the air from a source outside the boat. We converted an extra engine room vent to the outside air source for the Air Top 5000. There is a danger of bringing rainwater or even seawater into the heater with an outside source, so we fashioned a deep "belly" in the intake hose immediately after it routes aboard, and drilled a small hole in the bottom of the belly for drainage. There isn't a way for me to measure the exact ratio of recycled interior vs. exterior air, but the decreased amount of airflow (and noise) through the old cabin air intake encourages me to guess it may be close to the 70/30 ratio often considered ideal. All of the cold air return and hot air ducting was easy to assemble. It took as long to plan the exact route of the hot air duct and drill three new holes for outlets as it did to actually assemble the duct. Our old furnace had been installed on some theory suggesting that turning the forward cabin into an oven might accidentally warm up the main and aft cabins as well. Our new Webasto connects to two new vents: one under the dining table in the salon and the other in the forward bulkhead of the aft cabin. The first moment of truth: Approximately fourteen do-it-yourself installation hours had been invested removing the old heater and installing the new Air Top 5000. The time was at hand to see whether the time had been well spent, or whether portions of the job would need to be redone. I inserted the fuse in the positive battery lead, climbed up to the salon, and twisted the control knob to the right. A green indicator light in the center of the knob illuminated to assure me that there was DC current to the control switch: a positive beginning. A barely perceptible "tick-tick" emanated from the fuel pump, confirming that it had power as well. A slightly discernable draft in the cabin air intake fitting indicated that the heater fan was also working. Preliminary electrical indications all seemed OK. I climbed back down the engine room hatch to check the pressurized side of the fuel pump. Nary a drop, all connections proved sound and solid. After a few minutes, the furnace fan speed increased considerably. A good quantity of cold air was blowing through each of the three heat vents. Then, the system shut down without lighting. Had I not read the instruction manual, I might have erroneously concluded that there was a problem with the heater. (Or, far more likely, my installation). Webasto's manual warns that the furnace may not light on any of the first "several" attempts after initial installation. It takes a few start-up attempts for the fuel pump to purge all the air from the fuel supply line. The longer the line, the greater the number of attempts required. Each time the system failed to ignite, I would turn the control knob back to the "off" position, wait for a minute or so, and then crank it back to full on. On the third startup attempt, the Air Top 5000 fired up and heat began flowing into all three cabins. Yes! The second moment of truth: Just as my arm began to cramp up from self inflicted back patting; the heater shut down prematurely. "Maybe there was an air bubble in the fuel line," I thought. "I'll try it again." On a second attempt after the initial firing, the heater also ran for about ten minutes and then shut down. On a third, the same results. Clearly there was a problem, somewhere. What had I done wrong? An incidental glance at the DC distribution panel provided the answer. On a dark November day, I had almost every cabin light in the boat turned on, including some larger wattage DC bulbs in the engine room, to provide enough light for ease of working. The AC battery charger breaker had been accidentally bumped into an "off" position who knows how many hours before. Battery voltage was down to just barely above 12. On the basis of a calculated guess, I ran the main engine for a few minutes until DC voltage had returned to a point just below 13-volts, and then fired up the Webasto again. The system worked perfectly, and I shut it off at the switch about 45-minutes later. Conclusions: The Webasto do-it-yourself installation kit absolutely enables a novice to fit a forced air diesel furnace to a boat. With nearly all the parts and pieces needed for the job delivered in a single box, a simplified wiring harness, and a pre-engineered fuel pump assembly, many of the more difficult technical problems have been solved. There are a few minor issues with Webasto's presorting and sacking of parts, (I think they should be sorted and sacked by system), and a few portions of the instruction booklet could have been more precisely worded or illustrated. Unless a boater is certifiably dangerous around simple tools and low voltage wiring, the kit brings the installation process within the reasonable abilities of most amateurs. (Exactly as demonstrated by yours truly, a semi-klutzy mechanical amateur). Projects such as this often inspire greater respect for the professionals in the trade. A heater installation involves the fuel system, the electrical system, and a fair amount of mechanical fitting aboard a boat. As a do-it-yourselfer I had an advantage: I was already very familiar with my own boat. Taking a heater aboard an unfamiliar craft and accomplishing a good installation would be no simple task, and would require a broad technical understanding of marine systems. I learned a lot during the heater project, enjoyed the satisfaction of building a functional system, and can recommend the Webasto self-install kit to other boaters open to an interesting and rewarding, very doable, challenge. Thank you: Special thanks to Sure Marine in Seattle for providing me with the opportunity to test and review this self install kit. And, of course, thanks to Webasto as well. The Air Top 5000 is proving to heat the boat quickly and evenly, and operates with much less noise than the old unit it replaced. A great product, and an exceptionally enabling kit. (If I had tried to do this without the kit, it really would have been next spring before we got heat back aboard "Indulgence".) |
#2
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Excellent article Chuck. Thanks very much!
Gould 0738 wrote: Finally finished that forced air furnace installation. For either person who might have followed my progress through the first two installments, here's the third, (and thankfully final) item in the series. It sounds like you installed the new heater with an in-line fuse... does it not have a breaker on the panel? I added a set of three new breakers to our panel, two are for the heater & it's fans; the third is yet unclaimed. How was the old heater wired in? BTW I don't know if I mentioned our issues with installing the exhaust system piping on our heater- it was the most expensive & time consuming & irritating part of the project. Eventually I called in a welder, an expert marine fabricator who did a beautiful job putting the pieces all together... and with every bit of it welded, there is zero possibility of a CO leak... I don't understand how so many people cruise without heat. It's miserable to be cold, even worse when you're wet too. Fair Skies Doug King |
#3
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I don't understand how so many people cruise without heat. It's
miserable to be cold, even worse when you're wet too. Fair Skies Doug King We just spent two nights a Pouslbo. It got down to freezing Saturday night. Ran the Webasto, as there was nobody alongside where the exhaust was going, and the boat could be described as "toasty". There is a little less heat going to the forward cabin than I would prefer, and a bit more available in the aft cabin than we really need, but I have a couple of ductwork tweaks in mind that should reallocate the air flow. It sounds like you installed the new heater with an in-line fuse... does it not have a breaker on the panel? I added a set of three new breakers to our panel, two are for the heater & it's fans; the third is yet unclaimed. How was the old heater wired in? The old heater was wired directly to the battery, with a fuse located at the heater itself. The simplified wiring is one of the features of the do-it-yourself kit. If the same heater is sold to somebody who is supposed to know what they're doing- there is a "pre-wire" board available (essentially a combo bus and circuit board). |
#4
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Only works in port and with shore power.....but an 110 v electric blanket
can work wonders on a chilly night. Low cost and light weight. See your favorite Wal-Mart for about $30 to $60.00 depending on size and features. -- RichG manager, Carolina Skiff Owners Group on MSN http://groups.msn.com/CarolinaSkiffOwners .. |
#5
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On Mon, 29 Nov 2004 01:02:48 GMT, "RichG"
wrote: Only works in port and with shore power.....but an 110 v electric blanket can work wonders on a chilly night. Low cost and light weight. See your favorite Wal-Mart for about $30 to $60.00 depending on size and features. ============================================= With an inverter and decent battery bank (4 golf cart batts) you can actually run an electric blanket all night long while anchored out. We found that it made all the difference with late season cruising in the north east. In the morning we'd fire up the generator for an hour, recharge the batteries, make some hot water for showers and heat up the cabin with reverse cycle A/C. |
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