Also, I have seen the cost quoted for Webasto style pumps which is used in a lot of RV hydronic system in about the $2-300.00 range; with used ones for $100.00 plus, so I have been looking at alternatives.
In sizing pumps does anyone know what the typical flow rates for the pumps should be?
Any suggested tactics for power source 12v for cost, 24v for preheating or depend on house inverter and run 120v ac pumps?
Thanks
Flow rate is based 1gpm for ea 11,000 btu AquaHot told me ,check out the 12 volt solar pumps they are cheap and some might flow 4+gpm
Ours had the main Webasto pump as well as a secondary pump. The secondary pump was a Bosch electric coolant pump.
All were 12v. If you run 120v pumps you're losing efficiency and going to use more battery capacity. Can't see a good reason not to stick with 12vdc pumps.
The system has to have a pump for each zone or engine .the main circulating pump is to circulate the coolant for the Webasto it is not much good for the heat exchangers
Quote from: luvrbus on December 01, 2019, 11:29:02 AM
Flow rate is based 1gpm for ea 11,000 btu AquaHot told me ,check out the 12 volt solar pumps they are cheap and some might flow 4+gpm
Thanks that's a great piece of tribal knowledge!!!!
That also answers my 1/2 PEX (1.2 min/2.3 max GPM) verses 3/4 PEX (2.3/4.6) question that I had in an earlier post. The following link is where I found that info:
http://s3.supplyhouse.com/product_category_files/11448-Flow-Rate-Chart.pdf (http://s3.supplyhouse.com/product_category_files/11448-Flow-Rate-Chart.pdf)
Most RV and boats with engine heat recovery for water heating has the following layout:
(https://www.crystalpoint.com/cpdownloads/public/outgoing/Freds/CurrentWaterHeaterDiagram.jpg)
For preheating and thermosiphon heat recovery I am thinking the following:
(https://www.crystalpoint.com/cpdownloads/public/outgoing/Freds/PreHeaterDiagram.jpg)
However wondering if I should add a check valve to prevent back flow though the pump?
You have created an engine overheating feedback loop.
Front flow will be your issue, not back flow.
If engine pre-heating, why wouldn't you want the heat going thru the heat exchangers?
We're preheating an engine here, it doesn't take much...you works just fine making the trip through the heat exchangers first.
Happy coaching!
Buswarrior
Quote from: buswarrior on December 02, 2019, 06:36:06 AM
You have created an engine overheating feedback loop.
Front flow will be your issue, not back flow.
If engine pre-heating, why wouldn't you want the heat going thru the heat exchangers?
We're preheating an engine here, it doesn't take much...you works just fine making the trip through the heat exchangers first.
Happy coaching!
Buswarrior
OK not sure I understand why this would create an engine over heat situation.
The preheat scenario assumes you have a nice toasty cabin with hot liquid in water heater or hydronic storage tank and you need to pump warmed coolant through the engine to warm it up.
Some bus's have an additional inline pump to assist with heater circuit coolant flow to the front; so that there is an additional pump in the circuit.
I think I have such a pump in my bus so maybe for preheat I wouldn't have to add a pump, simply turn this secondary pump on to circulate engine coolant through the heat storage tank.
My concern for adding the pump as I did in the design was that unless it was energized; it would prevent flow.
So if the bus doesn't have the additional pump, it should be added inline and energized when driver heat is desired?
PS. I wasn't trying to show the entire system; just the engine loop portion as a starting point to a hydronic design with fully isolated loops.
Engine running, the hot coolant will go through your pre-heat pump and back to the cold side of the engine, but still be hot.
Heat exchangers present resistance, the short cut thru the pump will be easier.
There was no where for the coolant to shed its heat.
Engine temps rise, as the coolant entering is already hot.
The same mistake happens with uncontrolled hot water heating loops. Once the hot water tank has reached operating temperature, the coolant returns to the engine hot, again, having no where to shed its heat.
Self-inflicted wound is right up there with Treason...
Nobody gets on these boards and brags they ruined their engine by bypassing the radiator with their home brewed Hydronics...
Unbalanced reporting...
Sometimes "free" is far from it...
Happy coaching!
Buswarrior
Most hydronic pumps are a flow through design so no resistance ( or very little ) when the pump is off and you are driving down the road the heat from the engine can some what heat the coach if set up right . Then turn on the pump to pre heat the engine from the coach side heating source to heat the engine b 4 starting a cold engine .
dave
What we need is a proper pump catalogue, with all the specs, sizes of inlet/outlet, flow, pressure, power consumption, so we can make some informed choices.
Can't do good design without good info.
Happy coaching!
Buswarrior
Wouldn't 2 heater control valves work. One to control (stop) flow to the heater core and the other to control (stop) flow to the hot water tank? The control to the hot water tank could be thermostatically controlled to "close" at a pre set temperature so as to NOT dump hot water into the radiator(s) cold (cooled) water return curcuit.
Yes, and same as MCI, put them in the return line.
Cooler for longevity.
Happy coaching!
Buswarrior
Thanks guys, great feedback, wondering if the heat exchange for the water heater or hydronic storage should be down stream of the drivers heater core or upstream?
I guess I will have to measure the next time I fire the bus up (it's in a storage yard).
I don't see your preheat source in those drawings. Is it the water heater? That might not be enough.
On my DL the big solenoid is on the supply side and there's a manual valve on the return. This will eventually be changed up a bit but there are many options. As it stands though the interior heat controller shuts down flow once the cabin gets warm enough, which takes care of the bypass problem. Since the webasto is now switched on by the cabin thermostat, a reduction in engine heat which results in cabin cooling will cause the webasto to be fired off, providing more engine heat as well. Not sure if that is going to work well enough to keep the engine temp up so it will take some testing, but there might be a preset temp switch that controls that, I'll have to look.
But none of that is a problem, the issue is with excluding engine heat when parked. Currently a very inefficient system that will eventually be changed. In any case, all these pumps are centrifugal type. None are positive displacement. So all will backflow when unpowered. Only way to deal with that is with a valve or a check, and checks reduce flow.
To design a system that does everything you want it is often best to start with an all inclusive list of everything that you want, and use that to figure out how to get from here to there. But like electrical wiring you have to be mindful of your returns and recognize that water goes where it can go, not just where you want it. When those pumps don't run they may as well be straight pipes.
Jim
You get very little flow from the pumps (March) when they are not running
That is true but have you tried pushing water through them when they're not running? Pumps on a manifold; one pump running will pull water from the manifold source and backwards (pump will have pull from the pump(s) on the manifold and push from the return side of the manifold) through any pump not running. All of my pumps pump through a check-valve into their circuit. Two into floor sectors, four into toe-kick heaters and one into a ducted heater in my bus.
Quote from: Lee Bradley on December 03, 2019, 01:33:30 PM
That is true but have you tried pushing water through them when they're not running? Pumps on a manifold; one pump running will pull water from the manifold source and backwards (pump will have pull from the pump(s) on the manifold and push from the return side of the manifold) through any pump not running. All of my pumps pump through a check-valve into their circuit. Two into floor sectors, four into toe-kick heaters and one into a ducted heater in my bus.
I have the later model 50,000 btu (2007) Aqua Hot it doesn't have check valves
I read somewhere that if you are forcing flow through an non-powered pump that it should be magnetic drive pump which is loosely coupled. It also handles a jammed pump more gracefully...
I will probably go for a flow detector to turn on a less expensive pump. Automation is cheap with a Raspberry Pi and hopefully lots of people will use what I publish as a canned solution.
I'd much rather have a canned solution for a leveling system using the stock air bags. I think the coolant system lends itself to simplicity and basic thermostatic controls. The issue as I see it is that the demands for heat come from all over the interior plus the engine plus the water heater, making a centralized controller a bit complex to install. Then your control elements are large and expensive and there may be a lot of them. To say nothing about having to be a software engineer to fix the thing. So a cheap plug-n-play replacement with spares would be nearly mandatory.
The leveling system also lends itself to a simple solution using mercury switches but with only four corners and existing hardware seems a simpler implementation. A raspberry could have advantages.
Jim
Actually I missed used the word canned, I meant open source and performing the automation with Node-Red control flows, so that it's always upgrade-able and modifiable.
Um... for you maybe? For lots of the rest of us, if you can't just plug it in and use it the way it is without working through nested menus and computer screens it ain't gonna happen. Sorry, many of us just aren't on board with that stuff, missed the train, got caught looking at the scenery, sorta kinda accidentally stepped off kinda on purpose, etc, etc.
Jim
Quote from: Jim Blackwood on December 05, 2019, 11:11:39 AM
Um... for you maybe? For lots of the rest of us, if you can't just plug it in and use it the way it is without working through nested menus and computer screens it ain't gonna happen. Sorry, many of us just aren't on board with that stuff, missed the train, got caught looking at the scenery, sorta kinda accidentally stepped off kinda on purpose, etc, etc.
Jim
I will also show a manual control solution LOL!
PS. You can also hopefully draft a younger offspring to get involved?
Quote from: Jim Blackwood on December 05, 2019, 11:11:39 AM
Um... for you maybe? For lots of the rest of us, if you can't just plug it in and use it the way it is without working through nested menus and computer screens it ain't gonna happen. Sorry, many of us just aren't on board with that stuff, missed the train, got caught looking at the scenery, sorta kinda accidentally stepped off kinda on purpose, etc, etc.
Jim
As much as I've read about your plans to build/customize your HVAC system, I'd have to believe you have what it takes to work through the 'nested menus and computer screens' to accomplish any of what's being discussed. It's not really any more complicated - you're just substituting electrons for refrigerant. Learn the new syntax and don't look back.
Quote from: richard5933 on December 06, 2019, 02:32:36 AM
As much as I've read about your plans to build/customize your HVAC system, I'd have to believe you have what it takes to work through the 'nested menus and computer screens' to accomplish any of what's being discussed. It's not really any more complicated - you're just substituting electrons for refrigerant. Learn the new syntax and don't look back.
NOOOoooooo.......!!!! PLEASE NOOOoooooo.....!!! Um, see I have a long history with electrons, and more than in any other area it is liberally littered and scattered with the twisted remains of earnest attempts. The few successes have been dearly paid for in the byproducts of torturous experience. It just wears you out after awhile. The typical scenario is that it all goes great for awhile then at some critical point takes a hard left turn and goes downhill from there until I'm back at ground zero wondering what went wrong. Over 50 years now? Truly shocking! Now I'm not saying that stuff isn't great. Heck I just upgraded the SEFI in my '71 MGB sports car to the GM '411 ECM and hope to fire it up in the next week or so. BUT, if it malfunctions I will have 2 spare ECMs on hand that I can just swap out. That's about enough for me. And though the boy became a computer science engineer he won't work on my stuff. My few forays into programming were truly painful experiences, my brain just doesn't work that way.
I don't want more of it. I'd like less if I could, but there are just some things you can't have any other way.
This is a whole nother can of worms though. Thankfully there are a few signs that the computer wizards are beginning to realize that they need to make that stuff a lot more user friendly, so maybe they can reverse the trend. I hope so. The problem is that it's getting a little late in the game for it to do me that much good. So I'm really better off with stuff that I can fix with a soldering gun and a pair of pliers. Physical limitations are beginning to make themselves known and that microstuff is getting kinda hard to see.
Jim
(https://busconversionmagazine.com/forum/proxy.php?request=http%3A%2F%2Fwww.914world.com%2Fbbs2%2Fstyle_emoticons%2Fdefault%2Fpopcorn%255B1%255D.gif&hash=2b3aeb1c265ebebe084d05386337c33dbc28c160)
Quote from: Jim Blackwood on December 06, 2019, 07:06:51 AM
Physical limitations are beginning to make themselves known and that microstuff is getting kinda hard to see.
Jim
Hey Jim, just turn up the font size LOL!
Jim How or why would you try to computerize a MGB.
The only electronic part I have put on mine are electronic points because I cannot see good enough to set points.
The one good upgrade was the aluminum flow through head. it really turns a old MG alive.
The good thing a Mg did for me was it convinced Roxane "at Davids coach" that he needed one.
Now we are working on a MGA for him.
uncle ned
Oh, well I'm one of those Dastardly Engine Converters. Probably even one of the ring leaders Ned. My MGB has been V8 powered since '88 and presently sports a supercharged and injected 340 Buick. It ain't exactly stock. I've run EFI since about 2000, first Ford, then Megasquirt and now GM because the hot rod community now knows how to get the most out of the '411 controller, which has the capabilities I need. My fondest hope is that once I have the basic tuning done I will be able to just forget about it. One of the best things? That controller now goes for about $40 at the pick-n-pull. So spares are cheap, and swapping one out isn't much harder than changing a relay.
Jim
Still working on my design and in studying the documentation for my water heater I was looking at the following diagram and an idea occurred to me.
(https://www.crystalpoint.com/cpdownloads/public/outgoing/Freds/FlowDiversion.jpg)
The above diagram is basically creating a back-water channel, if you close valve number four then all the flow goes through the heat exchanger, if you open it all the way up then it takes the least path of resistance from point one to point seven.
So, my idea is to use the same strategy with the preheat pump by replacing the adjustable valve with a check valve.
(https://www.crystalpoint.com/cpdownloads/public/outgoing/Freds/PreWaterHeaterDiagramWithCheckValve.jpg)
And to prevent an engine overheating feedback loop, that buswarrior warned about; we add a preheat cutoff sensor that creates an open circuit at 70-100 degrees and cuts power to the pump.
You could also add an indicator light after the cutoff sensor that will be on while it is preheating and off when at starting temperature.
Jim Blackwood
You say you are 25% Farnsworth is that as in Dallas.
Or was Kat the Farnsworth great couple but like me different.
uncle ned
I think Farnsworth is the guy in the picture Jim has for his Icon.
Farnsworth is on the cartoon "Futurama". I personally like Bender, the wise cracking robot. I was thinking of putting one of his decals on my bumper, "Kiss my shiny metal ..." ;D
I am still in the bugs bunny and roadrunner days
uncle ned
Glad somebody finally got the reference. Hilarious cartoon. Sort of a wacky irreverent parody of The Jetsons. In multiple episodes Bender says, "I'm XX%" something or other. Just happens that I actually am 25% Farnsworth, so hey, why not right? W.Va. branch of the family, from around Buchannon. A great uncle was interrim Governor at the time of seccession. (Incidentally, W.Va. was the only state to succeed at secession.) So a lot of things just sort of fit together in a fun way.
Jim
Good News Everyone!
Edith has said she'd be willing to stay in the bus when we visit my family in Milton W.Va.! ( A significant departure from her earlier position) Most likely once the build is finished it'll go up there to sit on my lot by my brother's house and make road trips from that location.
Jim
Jim this one?
Daniel D. T. Farnsworth February 26, 1869 March 4, 1869 Governor of West Virgina for a time.
:)
Yep, he was an uncle and only in office for about a week, but while he was there he pardoned a nephew (another Farnsworth) who was an unreconstructed Rebel. (I had ancestors on both sides of that conflict) Good thing for me that he did, since otherwise I'd probably not be here. That particular ancestor was a bit of a scoundrel and was a particular friend of Frank James, who he apparently rode with for a time and who did some convalescence at the Farnsworth home following what was reportedly a gunshot wound of some sort.
Jim