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Message |
all2go
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, November 10, 2005 - 2:55 pm: | |
I read your post on the Hydronic Heater thread and would really appreciate some more detailed information. I just bought some US Military 30,000 BTU engine pre heaters and am planning on using two (redundancy is good) of them in my 4905. They are diesel fired just like Webasto/ProHeat/Espar etc. but not as fancy. Very nice brand new units with their own pump.
I would like to implement a system like you describe,
1inch+ finned copper heat tubing from HD. (is that Home Depot?) The finned tubing would run all the side wall of the coach, and return. 30 or 35 ft each way. The U-turn would be soldered 45's or refrigeration slow ells. (Very wide radius). When the thermostat turns on the Ivan labs or Marche tiny circ pump would take heat from the hot tank and pump it thru the baseboard lines.
Resistance would be low as the piping is so oversized. When the water cools enough the Paloma (in my case the preheater)would kick on , and the circ pump would continue to run. The real trick to getting this to work well is a shocker. Install the heating pipes FIRST! Then locating the tank & burner can use the fewest plumbing fittings , slowing down the circulation (increasing electric needs) the least. The tank would be ABOVE the heater so thermosyphon would assist the tiny circ pump during heat firing. The finished unit would be running the circ pump 24/7 with the interior temp controlled by the temp of the circ water.Or simply cycled by the thermostat operating the circ pump for LONG times. ON boats I have built oil fired systems that use thermosyphon and NO circ pump , but it would be too hard with the 30,000+ btu needed to heat a coach at below 0-F. Roll your own? Maybe if you really have a need for no power heat."
I have tons of questions for your expertise and anyone else who would chip in, good or bad. Can PEX be used for some of the parts of the pipe runs? I need to investigate PEX as I have heard it mentioned a lot...but can it be joined to copper? Compression fitting? Do 12v or 24 v fans need to be used or would the "radiator" effect be enough. What, in your opinion, would be the best place and how to integrate the two units, or even three into the Coach cooling system for preheating the engine also. Maybe just one for engine preheat? I still have the long 1" runs of original copper that were in the 4905 for the heaters, should those be used if they are ok, they did not leak. Of course many say copper should not be used, vibration, hardening etc..
I just pulled the heaters out and am trying to re-pipe and leave the original 24v water pump and defroster units intact. Is that even a good idea? I have heard some one say the old pump was noisy and should be replaced. 1970's technology. But it pumps very well and sometimes the old stuff is better made than the new. I have all the specs on it, I think it is 1/3 Hp. These units have their own circulating pump too. Would multiple pumps interfere or even be needed?
Would the preheaters be better all in one place or put a unit in the back where the AC compressor used to be, then one up front and possibly another in a middle bay? Connect them? No, do separate zones? I have the units and am eager to get started but if I just start designing with out some input (or expertise)it will all be wasted.
The statement you made "The real shame is a hydronic unit can be built that is far superior to the OTS stuff sold to heat truck engines.(these are Mil Spec, good stuff, and I know there is no support or warranty, it's hard to find parts etc..But the price is right!)
But if you can only buy , not innovate , your stuck with those noisy and ineficent power hogs,(these are , or seem to be, efficient) that cost lots of cash for inital outlay and all the required maint. Sorry, I cant help the helpless,”
I am not one of the helpless, but I would benefit from your years of experience if you would expand on your concept some more. I learn a lot from all you guys but a tad more detail would help. I have the units, the Coach and would be the Guinea Pig. I am up for some planning and fabricating. Not as fancy or costly as Gumpy. But a basic nice heating system everyone could purloin ideas from. Maybe then all the "do it your way" advice (from everyone...they all use your phrase now)could be a little more defined and some good systems designed and posted so we could all benefit from the experience out here on the board.
Electric, Propane, Diesel or Oil fired, everyone has their preference but a lot of the vague and nebulous details could be pinned down a little bit better. Hey! I'll send (you have to pay the cheapest shipping we can find, probably about $30 or less, they are boxed very well, 12 1/2" X 8 1/2" X 22" and 27lbs.) a free one of these units (The US paid $1800 each so it's a good deal) to the person that the majority of a general consensus says has the best idea for an Hydronic system using a Diesel Preheater type of source. Naming components and giving a plan from which one can be built, not just an idea. I bet there are lots of us that would like to see details.
The swimming pool/Hot Tub components, switches, relays etc are a great idea. I was tunnel vision on manual cutoffs and such until I read that and it opened up all sorts of opportunities. But, K.I.S.S. is important of course, of course, and no one can talk to a horse of course, (I couldn't resist).
So using them in necessary but limited functions would be best I suppose. Three of them in a Coach seems a lot, 90,000 BTU'S. Nice and warm. They use 18cc of fuel a minute on high (30,000 BTU's)and 13cc on low (20,000 BTU's). That seems to be about .01584 of a Gallon an hour on high. That is only .38 of a Gallon a day if it ran all 24 hours... and it wouldn't. Wow, that seems economical. (I know I'll get some replies now just to correct that math, 'cause it seems way too good to be true).I guess the amperage draw would have to be calculated into the running cost also.
I'll try to find a Website to post some specs of the units. I do hope someone has some time to be creative and use their hard earned AC/Heat experience. Anyone?
Andrew.
4905-393 |
Richard Bowyer (Drivingmisslazy)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, November 10, 2005 - 3:56 pm: | |
Andrew, It sounds like a great plan. I like your idea of listening to someone who has actually done it. You will hear a lot of BS here about great plans but nothing in the way of actual experience to back it up, so be very cautious.
My personal feeling is that three units is a lot of overkill and they really do not perform as well with only light loads. They cycle on and off to much.
My Webasto was more than adequate down to 0 degrees, which was the coldest temperature I was in and even then it cycled on and off quite a bit, so I am sure it would have kept everything nice and toasty at even lower temperatures.
I always had it circulating thru the engine also which wastes quite a bit of heat. Actually it circulated thru the genset and the engine radiator and the water heater also.
Richard |
Randall Hays (Bulldogie)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, November 10, 2005 - 4:39 pm: | |
Andrew, your right, it is to good to be true, 1 gal = 3,785 ml or CC's, so you would burn 6.8480 gal per hour or .285 gal per hour at the 18 ml per min. You might also want to invesigate the new house controls for your heat requests as they don't wait as long between cycles to turn on thus you stay closer to the desired heat that you require Randall |
all2go
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, November 10, 2005 - 5:26 pm: | |
Thanks Richard. That sounds logical about the units not being under enough load and cycling on and off too much. I guess I could keep one of them turned off unless really needed though. It all depends on how they are hooked up. Unless I set it all up there is no telling what is optimum. That's why it is great to here from people who have done it already. What size is your Webasto? These are only 30,000 BTU.
Andrew. |
Tim Strommen (Tim_strommen)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, November 10, 2005 - 5:30 pm: | |
Hey Andrew,
If you're in the middle of figuring out the heat-loss calcs, I've produced an Excel spreadsheet, that pretty much covers this. If you're interested, take a look at this link and decide if it's something you want (it's free but big - 6.5MB):
http://www.busnut.com/bbs/messages/6/11410.html?1131340489
Cheers!
-Tim |
all2go
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, November 10, 2005 - 6:20 pm: | |
Randall,
I'm lousy at math anyway so that is no surprise. Even using a calculator I get several different answers each time I run the figures. You are right it is .285 gallons per hour.
Ok now, please tell me, what does this mean?
"You might also want to invesigate the new house controls for your heat requests as they don't wait as long between cycles to turn on thus you stay closer to the desired heat that you require"
Boy this gets complicated. Are House Controls some kind of Code Book? and are heat requests a formula for calculating BTU's needed for a certain area to maintain a certain temperature? That almost sounded like I knew what you meant, but I'm still unsure.
Thanks for the input, I'm learning
Andrew. |
all2go
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, November 10, 2005 - 6:24 pm: | |
Thanks Tim,
That solves my dilemma with Randall and House Controls and Heat Requests...I hope.
Andrew. |
Jerry Liebler (Jerry_liebler)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, November 10, 2005 - 7:44 pm: | |
Andrew,
Though my bus is a bit shorter (5 ft) the defroster heater works very well without the booster pump, so I'd say simply bypass and eliminate the pump.
As to weather PEX is ok for a hydronic heating system, the answer is certainly yes, but. If there are any iron or steel parts in contact with the working fluid then PEX with an oxygen barrier should be used. Pex is widely used in hydronic systems.
One of the biggest challenges I faced in installing my Webasto system is locating and mounting the many pieces. I'm using 5 fan heat exchangers. I have an engine coolant heat exchanger (and engine preheat function) and a domestic hot water heating heat exchanger and two pumps (one for the main loop, another for the engine coolant loop). I mounted the Webasto itself and the engine heat exchanger in the engine compartment, above the transmission.
My hot water heater is under the floor extension, in front of where the step used to be. My resevoiur tank is neatly tucked in the rear cap on the right side. I used an electrically operated 3 way valve to bypass the fan heat exchangers yet allow hot water heating during the summer. As of now I have two zones, front and rear with a third for hot water. My system was a kit of parts supplied by Wirco.
Regards
Jerry 4107 1120 |
Jerry Liebler (Jerry_liebler)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, November 10, 2005 - 7:58 pm: | |
Andrew,
Though my bus is a bit shorter (5 ft) the defroster heater works very well without the booster pump, so I'd say simply bypass and eliminate the pump. I'm using the original pipes.
I 'teed' my engine coolant heat exchanger into the engine cooling system below the valves in the engine compartment.
As to weather PEX is ok for a hydronic heating system, the answer is certainly yes, but. If there are any iron or steel parts in contact with the working fluid then PEX with an oxygen barrier should be used. Pex is widely used in hydronic systems.
One of the biggest challenges I faced in installing my Webasto system is locating and mounting the many pieces. I'm using 5 fan heat exchangers. I also have an engine coolant heat exchanger (and engine preheat function) and a domestic hot water heating heat exchanger and two pumps (one for the main loop, another for the engine coolant loop). I mounted the Webasto itself, the engine heat exchanger, the fuel filter and both pumps in the engine compartment, above the transmission. My Webasto exaust exits under the rear bumper on the right side.
My hot water heater is under the floor extension, in front of where the step used to be. My resevoiur tank and water filter is neatly tucked in the rear cap on the right side. I used an electrically operated 3 way valve to bypass the fan heat exchangers yet allow hot water heating during the summer. As of now I have two zones, front and rear with a third for hot water. I ran a seperate fuel and fuel return line through the tunnel. My system was a kit of parts supplied by Wirco.
Regards
Jerry 4107 1120 |
Stan
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, November 10, 2005 - 8:14 pm: | |
Just a few ideas to start with. It is almost impossible to calculate heat loss on a bus. Just remove as much glass as possible and then insulate the walls, floor and roof as much as practical. Park it out of the wind in cold weather.
The 3/4" copper tube with 2" square aluminum fins will radiate about 900 BTUs per foot. With a well insulated bus you will need about 25'. If you have wall space for that much fin, you don't need any fans or toe kick heaters. For that much fin, you have to use a circulating pump. |
DMDave
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, November 10, 2005 - 11:30 pm: | |
Andrew, check out George Myers Coach Builders Bulletin (link on this site) and get his Heating with hot water book. Its very good. Pex has adapters to copper but not sure of largest sizes Pex comes in. When we install radient heat Pex we usually use 1/2" and it comes in 300' rolls. I have some scrap pieces if you want some. Baseboard usually comes in 3/4 copper but you can get high output (80A). It has larger heavier fins. I think the house controls they are talking about are just Digital Thermostats for your home(30-50 bucks) that can turn on your relays and such. My ? is, is it cheaper to run a gen set and electric heaters? It seems to need a lot of elecricity and diesel juice to run a hydronic system. Also note Don Konig used a Poloma LP for a hot water system. His article is in Vol 3 issue 1 in the coach bulletin. |
joe padberg (Joemc7ab)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, November 10, 2005 - 11:56 pm: | |
Andrew, I am also very much interested in learning some of the practical aspects of a heating system. My ideas have changed on several areas, after frequenting this board for the last couple of years. Have decided to go propane for heating with wet baseboards. I was able to find a Bosch heater which will become the heart of the system and I allready had a 90 gallon tank before i got the bus. I am anxious to start working on the bus, since some of the other projects are just about complete. Sunroom and kitchen for the wife. Tomorrow I hope to get most of the isulating done on the busbarn, sowe are getting close to moving the beast inside. Joe. |
Randall Hays (Bulldogie)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, November 11, 2005 - 12:12 am: | |
Andrew, If your going to control the heat in an area then you will need a control to turn your pump on and off. The controls that are sold and HD and Lowels are compterized House Controls for the home and instead of the long times between turning on the heater and it being off, which happens with the spring loaded mercury switches they now use the compterized controls, hope that helps explain it Randall |
FAST FRED
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, November 11, 2005 - 5:23 am: | |
"The swimming pool/Hot Tub components, switches, relays etc are a great idea."
You have missed the POINT of the concept , silent heat with minimal electric,
Once you leave the smooth walls of copper tubing with switched valves zone controll and all the rest , the SIZE of the circ pump becomes a power hog.
The military surplus stuff has very little backup in terms of parts , ask Geoff , who did a fine job of creating a schematic for one , but heaved it for RV OTS.
2 long runs of tubing is required as the heat transfer is far lower at 135 or even 115 (insulated windoes) than at 180 where most BTU transfer is calculated.
Will it work , yes ,
BUT will you want to maintain an orphan?
Ca$h vs time and frustration?
FAST FRED |
Tim Strommen (Tim_strommen)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, November 11, 2005 - 6:02 pm: | |
"Heat Requests" - this is the state at which the thermostat has determined that the tempurature in a space is lower than the set-point.
With old fasioned thermostats, there was a tempurature sensitive multi-metal-sandwich spring coil that had a mercury switch in the middle (by using different metals with different themal expansion, you can calculate the lenghth of one metal compared to another and predict the "twist" it will put in a spring). As the position of the spring relates to how fast the metal equalizes with the ambient tempurature, there will be a delay in the response to the set-point (can be 2-7 degrees). Also, there is a delay between where the tempurature is above the set-point and when the spring stops the heater (the mecury ball rolls to the other end of the glass capsule, breaking the contact). This can make the tempurature go above the set-point by 1-5 degrees - giving you a total temp difference of 10 degrees or more in extreme cases.
One more thing to consider is that because the mercury thermostat relies on a steady state of phyisical location (it is assumed that the wall of a house isn't going anywhere) even the motion of the vehicle could falsely/repeatedly trigger the heating system in extreme cases.
Solid state themostats can be made very fast and very accurate by the use of high-thermal conductivity heatsinks mounted to the probe's case. This not only inproves the thermal absorbtion time of the probe which makes it faster, but makes it more accurate by disapating most of the "self heating" that occurs with probes. Thus tempurature differences can be nailed down to about 2-4 degrees total. They also don't care about the motion of the wall as they are not based on any moving parts.
However this all assumes that you put enough thought into where you are placing the probe. If you put it right under an A/C vent it'll think "JEEZ its cold in here!" and turn off the A/C (or vise versa with the heater - but the same concept
Some of the newer thermostats support multi-level/stage heating and cooling so that the heater doesn't need to be on full-blast when the temperature difference can be managed with half-power. And there are even some that can varry the speed of the fan (if used in a system).
Cheers!
-Tim |
all2go
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, November 12, 2005 - 1:45 pm: | |
Thank you everyone,
I will forge ahead with my system after reading the info suggested. Lots of experienced advice there that was illuminating. Now I know more about what to aim for.
Andrew. |
Tom Caffrey (Pvcces)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, December 07, 2005 - 12:28 am: | |
I know of a house here in Ketchikan that has a boiler in the basement and large radiators in all the larger rooms. The thing that is different about this home is that all the radiators are fed by 2 inch iron pipe.
This was done so that the boiler system could be made efficient. The thermostat makes the burner run, which causes the water to circulate by gravity.
This means that in mild weather the boiler only runs warm. In colder weather, the boiler runs warmer. It reduces waste due to high flue losses.
The drawback is that it is not designed to heat quickly. Instead, the weather changes, but the house doesn't. This works best with the thermostat left alone most of the time.
For economy, allowing the house to cool at night and during the day when no one is home could save some fuel, but you need quick heating if that is to work.
If this system also had an extra source of heat for raising air temperature quickly, it might be the best of both worlds.
For an easy way to remember heat capability, one gallon per hour of diesel fuel can provide heating roughly equal to 20 portable electric heaters. Which is why Alaska heating is mostly done with fuel oil.
For what it is worth.
Tom Caffrey PD4106-2576
Suncatcher
Ketchikan, Alaska |
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