Camper heating

[Tony LEE]

Yes, always a technical solution possible, but at a dollar cost and an increased risk of failure with often no way of fixing it in the field. Also being a self-funded retiree with no more easy access to sophisticated components at the "right price", I tend to go with the low-tech solutions wherever possible. I also don't use car heater valves either simply because a standard manual ball valve does the job with the way I have it set up AND it is a hell of a lot easier to install. For instance, I can leave the engine coolant line valve always just cracked enough so the calorifier is hot enough for the evening shower after a couple of hours driving, yet there isn't a huge waste of money in also heating the engine at night when we really just need house heating and it serves to reduce short cycling AND the engine appreciates the warm start next morning. Similarly, the three fan heaters balancing valves and their main isolating valve are left in the same position even when we just need water heating - just don't energise the fans. The fans are also controlled by a wall thermostat leaving the webasto to do whatever it wants. If the engine is supplying the heat, I can leave the fans running so the house is nice and warm when we stop to set up camp. If I really want to alter the flows to achieve a certain effect when setting off for the day, the access door to my plant room is right next to the drivers cab door. Wet clothes hanging in the bathroom and want them dry after the day's travel? Just run the bathroom fan and direct engine coolant through that heater.
Works because this vehicle is solely a winter desert vehicle and when the temperatures rise, we just go somewhere more pleasant for a few months.

BTW Rarely run the heater all night. Electric blankets are quieter and cosier and don't hammer the batteries much more than the heater and fans would.

Just remembered that another reason for not using electric valves was they didn't seem suitable for low pressure-drop circuits because they were diaphragm valves with fairly high minimum pressure drop requirements.

 

[SkiFreak]

I hear everything you are saying and agree that the KISS principle has many merits. It sounds like you have a very simple, yet workable solution.
As I said... if I were designing my system again I doubt that I would go down the same route I have gone.
Having said that, I think that what I have now is very robust and should see many years of service without any major issues.

 

[Tony LEE]

I have to remove the header tank to fix a tiny leak so will have to remove all the junk stored on top. Then I'll take a photo after I use Brasso to polish up all the brassware.

Those intending to use a calorifier should do their homework. Some of them are well insulated and some are extremely deficient. There is a test report - bit old now perhaps - available on the internet and the performance varies hugely. Mine is one of the latter and the next job is to bury it in extra insulation - and yes, all the pipes are turned downwards and the elbows insulated to reduce thermal syphoning.

 

[whatcharterboat]

Yeah, Hi Tony....just on your comment about calorifier insulation....just thought I would add that some calorifiers are also designed with the insulation thicker at the top than at the bottom....in other words they are specifically designed to be mounted only one way and if design of the camper requires the calorifier to hang from under the floor or be wall mounted then insulation efficiency will be compromised.

Regards John.

 

[gait]

FWIW the car heater valves I used (like the ones in the eBay link) are simple ball valves. Just had the tails that the heater hose fits. I haven't added the choke type push/pull cables (can never remember the techie name for them) to operate as they are easily accessible. In operation I open/close the engine connection and open/close water heater connection - something I read somewhere and in cold weather it made sense to push all the engine heated water to where its needed.

 

[Tony LEE]

Yes John, that is likely correct and it would be a sensible design to have more insulation on the top half if there was a top half. Mine was to be mounted either on its feet horizontally on any surface, or could be mounted on a wall with the long axis vertical using the tube supplied to fit inside the outlet tube so I imagine it would have uniform thickness all over.. It is one supplied by Webasto, but not the one shown in the report. I'd say the model I have still wouldn't deliver any water over 40C after 2 hours heating and 12 hours sitting as per the test. If I drape a couple of towels over it, the temperature of the top surface of the heater under the towels is quite high indicating to me that the insulation value of the two towels is not much worse than whatever the tank is coated with. Not scientific I know, but it suggests that a few layers of foil-covered bubble wrap or similar and some aluminium tape might make a fair bit of difference.

Regardless of a couple of minor deficiencies eg the deafening fans supplied with the fan heater that three others including gait have ditched in favour of quiet ones, the hydronic system as generally described in this topic does work and makes life much more pleasant. I was hoping to take the OKA to S America so tried to make all the tanks and piping as freeze-proof as possible by installing everything inside the outer shell and where I couldn't avoid running a couple of pipes outside, they are insulated and trace-heated so when they do freeze, it won't take much to unfreeze them. AQIS antics have put me off a bit so the OKA will likely serve out its (and our) days spending at least a couple of months a year in the deserts.

Cooktop is also diesel - and that topic is a little more controversial than diesel heating.