Thermostats

[Jim Blackwood]

I'm curious what Busnuts are using for thermostats since my Espar 99 hour timer decided to quit again. The hydronic system really needs a thermostat more than a timer. There is a square controller mounted in the pod with it but I haven't been able to figure out what that does. All it has is a knob and an indicator light and I can't tell that it does anything at all. At least with the timer it has 3 wires and I can short two of them together to fire up the Eberspaecher heater. So I figure I should be able to connect just about any old sort of thermostat to those and get it to work. Or a toggle switch.

Jim

[richard5933]

On our 4106 I just used a low-voltage simple wall thermostat.

[sledhead]

in my house garage at home I have a regular thermo. and a 1 hr timer as well that will turn it on . so if I want instant heat with out touching the thermo. I just spin the timer for a few min. or 20 min . or so and it makes it easy for instant heat . this is on a boiler system .

I like the old style turn timers I have one on a exhaust fan as well as one on the fuel tank pump . I never need to worry about going back and turning it off later   

[chessie4905]

Electric heat thermostats also work well.

[Jim Blackwood]

I think I may have found a good one:

https://www.ebay.com/itm/302165113506

About $10 and available in 12v and 24vdc versions. Should be here in a week or so.

Jim

[richard5933]

Nice solution. I could have used something like that when I was trying to Macgyver something to keep our old 12v fridge working after the thermostat quit.

Does it allow you to set an offset? If it doesn't, the only problem I see is that it might cycle things on and off way too often for the Espar to be happy.

[Jim Blackwood]

Hard to say. There was no real documentation on it so I'll have to wait and see. For ten bucks I figured it was worth taking a chance on it and maybe I can use it for something else. OTOH, if the offset can be set that'd be pretty sweet. What I'm thinking though since it's run from a local sensor bulb is that the environment may provide enough hysteresis to keep the burner happy. That may be a thin reed to place my hopes on since a 3 minute cycle-down is programmed into the burner but it may tolerate less than that on restarts.

Jim

[buswarrior]

What are the consequences of controlling liquid temperature instead of flow, for temperature control?

I'm wondering if greater than desired temp swings, waiting for it to stop and start...?

Control the liquid temperature or control the flow?

Where's the HVAC guys when we need 'em?

Happy coaching!
Buswarrior

[Geoff]

I have a Webasto that can heat the interior (and water heater) and/or preheat the engine.  The Webasto runs off a on-off switch and while on maintains the antifreeze at 140 degrees.  I have two large heat exchangers inside the bus that run off a wall thermostat.

So my system does not shut down the Webasto, it runs and is always keeping the coolant at 140.  I don't think the Webasto would be happy getting shut down off a wall thermostat and restarting again and shutting down time after time. 

What I have found is that just having the hot antifreeze circulating inside the bus keeps it cozy without the fans coming on.

[chessie4905]

If that electronic one doesn't work, maybe this Honeywell would work. They don't use the anticipater any more. Instead they have dip switches with four possible settings depending on your heat source. It appears that each setting allows mor or fewer burning cycles at unit temperature setting. Works well for our house.
https://www.amazon.com/gp/product/B000EANORW/ref=ppx_yo_dt_b_asin_title_o09__o00_s01?ie=UTF8&psc=1

[Jim Blackwood]

Oddly enough, there seems to be more going on here and I suspect I'll be spending more time with the schematics. I had the bus running for maybe an hour last week while I removed the Esper controller. It never once turned on the manual mode and I had it unplugged for most of that time. When I shut down the bus the pump was running and the burner was warm. Didn't check the exhaust. (oversight there really) But if the pump was running doesn't that say it was in it's 3 minute shut down cycle, so the burner had been running trying to get the coolant up to temp? I'm sure it doesn't runn all the time the engine is on, so there has to be something other than the 99 hour timer turning it on.

Then there's that blank faced controller next to it. Does that run the dash blower, or is there a coolant sensor? OK I need to answer that question before this goes any further.

The way I would like it to work is for it to keep the coolant warm until the cabin gets up to temp, then whether it cycles on/off or not is a good question. Maybe that depends on how cold it is outside? I'd hate to be running it all night if it's 50 degrees outside.

Jim

[richard5933]

You might have a water temp sensor that looks like this in your system. Could actually be a couple of these. This is how the system knows the temp of the water in the loops. Our wouldn't run at all until I found this puppy and got a new one. Then I installed it wrong at first, and the thing wouldn't shut down. Not sure if this is related to what you're experiencing, but at least it's something to look for/at.

[sledhead]

all the boilers I have had work on a switch and cycle on there own . on the rv aqua hot I installed a timer and a small led light so I could see and keep track of how long the burner was on . this way if I want to turn the unit off I wait until the light turns off so to make sure the burner has finished it cycle and I do not screw up the burn and cool down . the thermostat controls the pump and fan for the heat side of the system

dave

[buswarrior]

Did you determine what control is regulating the coach interior temp?

IIRC, that square one by your Espar control belongs in one of the holes to the right of the steering wheel.

Where it is mounted now, is where a Webasto brand timer goes on other D models.

You want an indicator that the boiler is burning, whether commanded by the timer, your home brewed controls, or by the engine, so you can at least know it is being commanded by something.

The Espar's job is to burn when the coolant is cold enough. Cold start and idle the bus, it is supposed to come on shortly after the start, and bring the coolant up to the cut-out temp, 160 degrees or whatever it is.

Is there no dash indicator, "aux heat" or something like that?

Happy coaching!
Buswarrior

[Jim Blackwood]

HA! Excellent question. Turns out the right side enunciator panel does have (according to the operator's manual) a green "Heater On" light. I will check that out. Thank you very much. Takes awhile, doesn't it?

There IS a vacant square hole a bit to the right of the wheel. Manual says, "Blanking plug" It also shows different control units from the ones I have installed in the pod as "Optional". Not much of a surprise there. I am considering moving that plain faced square controller to the vacant hole and eliminating the pod.

So it does make sense that the boiler could sense coolant temp and run based on that, provided the master control switch is on. Probably built into it rather than a separate sensor somewhere, but could be.

Anyway the left side controller should be for dash heat so I guess it makes sense for that to only run the dash blower fan except I don't think it does, and the driver has a cable operated water valve to control coolant flow. Another thing for me to check. Which leaves the Espar timer for preheat. I could probably set up this little thermostat to take the place of the timer and as long as it didn't do rapid cycling once the cabin got warm I guess it would work. Might need something to keep the fans from running until the coolant gets warm, maybe that could be slaved off the water pump. Too bad there isn't a light to show when that is running, but maybe I could use the LAV Emerg light and circuit for that.

But what I don't quite get is why that plain faced  controller is even there on the left. So far only one thing even begins to make sense. The fresh air control. There is no T-handle for that. Never was, no holes for it. Part of the cable is there though, the end that hooks to the damper. It has been cut off. What did it hook to? Don't know, that part is gone. Maybe some sort of actuator? Maybe the actuator was run by the plain faced controller? At least that is my theory at this point. Think I could get any answers out of MCI?

Jim