Last winter we had a reverse cycle heating and air conditioning system installed by the good folks up in Gratitude. At the time we were thinking more about A/C than heat because we hadn't even considered living aboard full time yet. Now that La Vida Dulce is the place we call home things are viewed from a different perspective. We've been very aware of the approaching winter and are doing everything we can to ensure we'll be toasty warm and cozy when it's 20 below outside. The main focus is heat (duh). The reverse cycle system uses the water we're floating in to make hot or cold air. It's only good as long as the water temperature is above 38 degrees F. Usually by January it has dipped down into the 30's or completely frozen over. We could use electric space heaters but the power at the dock has a reputation for being shut off periodically through the winter and it's limited to 30 amps so we're gonna need something else.
Espar makes a series of forced air and hot water diesel heaters. Check out this video on how the forced air heater works (
click here). We chose a kit that includes a D5 forced air heater with enough ducting, fittings, vents and hardware to complete a system for a 45' boat. When we went to pick it up from Annapolis Cruisair (
web site) we found a huge box on a pallet that would barely fit into our Ford Escape mini SUV. Once we got it down to the boat we found a very complete system but very poor installation instructions. I suppose this is because each install is unique but there could be more info on common things like what size holes to cut for the duct work and suggestions for mounting the heater. I guess these kits are really meant for professional installers. Looking on the Espar website for some ideas, I found a video on how to install this thing.....in a tractor trailer. Apparently these are used mostly by truckers to keep their berths toasty when they stop for the night, saving fuel by not running the engine the whole time.
I read through the book which was mostly about government regulations in Germany, safety concerns and hazards of working with electricity and about diesel fed fires. OK, so I'm not going to get much help on this project. I decided to be really organized and plan everything out ahead before I started cutting holes in the beautiful teak cabinetry. It appeared that the best route for the duct-work would be through the cabinets on the port side. I wanted to mount the heater in the cockpit locker and run the duct under the aft cabin bunk, jump over to the cabinets and then run forward from there. Cheri didn't like the idea of the duct showing where it poked out of the bunk and I told her it would be boxed in so it wouldn't show. She asked how many years would go by before I got around to boxing it in. OK, plan B.
I looked into running the duct down the starboard side. We'd lose the ability to heat the forward head going this way but we figured we could live with that. I spent an entire day crawling around the boat before I nixed the idea of running the duct down the starboard side. The refrigerator's location makes it pretty much impossible to run any ducting down that side without having too many tight bends and taking up too much storage.
Plan C. I spent another two days emptying out cabinets and crawling around under the cockpit before I settled on a definite plan. I'd attach a plywood shelf to the inside of the hull in the port side cockpit locker. The heater will be mounted there and the supply side duct-work would go through the bulkhead into the aft cabin coming in just under the shelf above the bunk (This will have to be boxed in but will make the shelf deeper and more usable. The idea of running the duct under the bunk was nixed because of tight bends required and space issues). From under there the duct enters the aft stateroom cabinet and hanging locker, goes through the bulkhead into the aft head and continues through cabinets all the way to the forward head.
I'm using a 4" hole saw for the 90mm duct and a 3.25" hole saw for the 75mm duct. There will be four vents; aft stateroom at the base of the hanging locker, main salon at the base of the settee, forward stateroom at the base of the hanging locker and forward head low on the bulkhead next to the sink. Where each vent branches off from the 90mm duct there is a "Y" and the vent line is reduced to 75mm duct. This makes it nice for snaking the vent lines and the larger main duct can be kept higher up in the cabinet towards the back and out of the way.
The heater uses a 90mm return line that will be run from the galley at the base of the refrigerator. This should help to circulate the air throughout the boat without having to run additional vent lines. The thermostat / control will be mounted at the Nav Station. Each of the vents are fully adjustable and can be closed down to adjust the flow and rotated to adjust direction. Pretty nice.
OK, so after I scoped out the location for the duct I began cutting holes and running the primary duct. Once this was in I sat down and read the manual again. I somehow missed the part where it explains how to plan the duct work. Espar has assigned a numerical value to every component. 90mm duct is given a number based on it's size and length. A 90 degree bend has a value. Reducers have a value. Vents have a value. The heater itself is given a value of 10 and you're supposed to add up everything else in the primary, secondary, and return lines and keep the total under 10. This is because restrictions in the ducts accumulate and create a backup at the heater, which, in turn, creates excessive heat buildup. I went through my design and found it's total to be 14.75. That's not gonna work. I re-thought what I had, made some changes to the parts that hadn't been installed yet, redirected one section and came up with 8.0.
Originally I had all four vent lines (secondary) being reduced at the "Y" to 75mm and running to a closeable vent. The biggest change I made in the design was having the primary run with 90mm duct all the way to the Main Salon where it ends with an open vent with a metal grid over it. I suppose the grid is to keep Bella out of the ductwork (I wonder what kind of rating they'd give her!). According to the book, for my calculations I can ignore the other three secondary lines because they can be considered closed. When they're open they reduce back pressure even more, which is a good thing, but with just the primary line running we're now in a safe pressure zone.
With this taken care of I ran the rest of the ductwork over the weekend of 12/4. I also changed the outlet location in the forward head once I got the ductwork up that far and realized my original plan wouldn't work. With this project ya gotta be flexible. I ended up running it through the wall behind the sink and exiting the cabinet just under the shelf behind the toilet. With the supply ductwork installed the worst part of the installation is over but I still have a lot to do. There's a return duct to put in, which'll run either to the Galley or the aft cabin, haven't made up my mind on that just yet. Also have the fuel line to run from the tank to the heater. And there's the control and power wiring between the Nav Station and the heater. And then there's the exhaust hose which requires a hole to be cut in the transom. Also need a fresh air intake for combustion. Oh yeah, there's also a drain line to the bilge from the heater. Hmmmm. I guess I still have a bit to do here.
12/12. I spent all day Friday and Saturday working on mounting the heater in the cockpit locker. The plan was to build a plywood shelf that it could be bolted to and attach that to the inside of the hull. This would put the heater in a good position to attach the supply and return ducts and give plenty of room for everything. Good plan. I formed up a mock-up for the shelf out of cardboard and duct tape and spent a lot of time matching the curvature of the hull. This was important because I planned to attach it using 3M 5500 and then glassing it in for additional support. Once I had the cardboard form to my liking I copied it onto some plywood, cut it out on the dock using my new handy dandy saber saw, and then mounted it with duct tape to check out my work. Not even close. It was way out of level for one thing and seeing it in action made me realize that this just wasn't going to be strong enough to hold that heater. The heater weighs about 25 pounds and I pictured it breaking loose in a heavy chop out in the middle of the Bay. Plan D. I moved the mounting location to a plywood bulkhead which places the heater "port and starboard" instead of "fore and aft". It also adds some bends in the duct work. I think I'm still in the "safe" zone with my math calculations though and I feel the mount is way stronger.
The following Tuesday while I was at work I realized that progress on this project was going way too slow so I took Wednesday and Thursday off to try to wrap it up before the really bad weather hit. That night the really bad weather hit. At 0400 I woke up to find the cabin temperature was down to 56 degrees. The reverse cycle system had called it quits because the water temperature had fallen below 38 degrees. The heat exchanger looked like a block of ice. I think I musta had a vision when I took that time off. As soon as I realized there was no chance of getting the heat exchanger going I got to work on the diesel system.
The first thing I did was cut holes in the bulkheads for the return air duct. I hadn't really planned this part out until now so I kept it easy and ran it to a high spot on the aft bulkhead of the aft cabin. This will draw the air back through the boat and hopefully help to heat this section of the room at the same time. It's also the easiest way to run the duct. I had originally wanted to run it under the reefer in the galley because it would have helped to evenly distribute the heat to the other side of the boat. This option would have required way too much effort and I just didn't have the time for that now. Easy is good. So I got the return duct hooked up and while I was in the cockpit locker I also ran the combustion supply and exhaust lines and wrapped the last with braided fiberglass mat as an insulator. The exhaust line can get smokin' hot so it's a good idea to protect everything around it from melting down. Once I got this done Cheri and I ran the fuel line. The kit comes with a coil of copper tubing to be used for this but I found it to be about 10' short so we went out and bought a 50' roll. We ran it under the cabin sole from the fuel tank, past the engine, out through the generator compartment under the cockpit and into the locker. Here it connects to the fuel pump and then runs up to the heater. The fuel pump needs to be mounted at an upward angle between 15 and 35 degrees to keep air pockets from forming which would kill the fuel pressure. For the connection at the tank end we used a special fitting at the top of the fuel tank and ran the riser tube down through that, cutting off the bottom at a 45 degree angle so it sits about 2" off the bottom. That'll help to keep tank grunge out of the line.
With the fuel taken care of it was time to run the power and control lines. The kit comes with a nice bundle of wire that's connected at one end to the heater through a pre-assembled multi-pin connector. From there it branches off into three bundles; fuel pump, power and ground, and a 6 wire bundle to be connected to the thermostat/control. All of these required adding connectors of one type or another. The fuel pump and power went fine. By the time I started in on the thermostat line it was 2000 (8pm) and I was getting pretty tired. This line uses a six pin connector that requires adding pins to #18 wire and inserting them into a two piece connector. Once the pins are in they have these little prongs that pop out on either side to hold it in place. I'm sure there's a special tool that costs $150 to use for these pins. Using a cheapo wire stripper doesn't cut it because the pins are so small that it's hard to get a good crimp on them. I ended up not using the connectors and just soldered and shrink wrapped the wires.
Update: I later needed to remove the thermostat control from the Nav Station and had to cut the wire to get it out. To reinstall it I used Deutsch connectors (
click here) and was so impressed with the quality I've continued to use them in other parts of the boat. The best example of this is at the mast where a large number of wires need to be disconnected for unstepping the mast.
With the control line connected we fired up the system. This took three attempts before it finally fired because it takes a while for the system to draw fuel through the line. Once it fired though, we had heat. Woohooo!
We did run into a few problems afterwards. The system kept shutting down and didn't provide any error codes. It would reset OK but would run for half the day then shut off again. We eventually found out that the factory preset is for a ten hour operation. I'm sure this is a safety thing for when the heater is installed in a truck. Not what we need in a boat though. To reset this you have to go into the program and reset it for continuous operation (
click here and scroll to page # 11). This isn't mentioned in the users manual and we only found out about it by going to Annapolis Cruisair for help. A second problem showed up after the system had been in operation for about a week. It stopped running, gave an error code of 13, would manually reset again and then only run for about 15 minutes before quitting. The owners manual only gives four error codes and this isn't one of them. We called Bryan at Annapolis Cruisair on Christmas Eve and he wasn't familiar with this code. He spent a good portion of his day getting in touch with a factory tech and finding out what this meant. Turns out the problem is with the airflow being restricted and causing hot spots in the heater. There are two internal sensors that compare temperatures and if there's too much variation they shut the system down. The tech said we probably have some really tight bends in our ducts. Gee, he was right. The return line that I put in during the mad rush to get the system running was the culprit. I removed the duct from the heater and let it run open for three days and never had another problem. Of course now I've got a system that needs to have the cockpit locker open when it runs so it doesn't suck bilge air into the Main Salon. Next week I'll work on rerouting the return duct so it doesn't have any restrictions.
Update: I ended up running the return duct from the starboard side of the aft bulkhead in the aft cabin into the starboard cockpit locker. It runs beneath one exhaust hose and then circles around behind the cockpit into the port side locker. There I re-mounted the heater unit on the inside of the hull so that both ducts, supply and return, both have a more direct run with no sharp turns. The mount for the heater is made from 3/4" plywood and is epoxied to the inside of the hull. The 2 part epoxy I used is from West Marine and includes a filler so when you squeeze it out and mix it up it's thicker so it won't tend to run out so easily when you goop it into place. Never-the-less, I used masking tape to hold it in place for two days until it dried. For the best explanation of my shelf style bracket see the drawing on the left.
So I learned that the Espar number planning game is real and you really do have to stay within the limit set for your heater. In our case this was 10. When I scrambled to finish the system I cheated and added too much restriction. Overall, I'm really impressed with this do-it-yourself kit from Espar. The instructions are kinda lousy but the system is simple enough that it's not too tough to figure out for yourself. The actual installation is pretty involved but the worst part is unloading all those cabinets and cutting holes in that beautiful teak. Once you get started it goes pretty quickly. You just have to spend the time in the beginning planning it all out.
I also want to say that I'm impressed with the people at Annapolis Cruisair and Espar. I called Bryan on his cell phone and interrupted his personal time with his family on Christmas Eve. He was very gracious and went out of his way to get us an answer to our problem. He contacted the Espar tech at his home and worked with him to figure out the problem. Bryan then called me back and offered several possible solutions but felt the duct restriction was the best possibility. All this on Christmas Eve! These guys sell a quality system and provide unbelievable support. Highly recommended.
