;VENTILATION OR DEATH
One of the key issues in a campervan is removing water. Water being in lots of places that it shouldn’t be. No matter how well you insulate your van, there will be always be condensation surfaces. The vans themselves will always have little corners here and there that are poorly ventilated (mould hates ventilation). Many things in a van add water.. c.900ml/day water is perspired/exhaled on average per person. So at peak occupancy over 8 hours, 2 people and one smallish collie will be adding well over a pint of water to a pretty small box. Add to that wet clothes, washing up, cooking (for which ventilation is pretty important…)..
In general, the answer to this is more ventilation and massively overpowered heaters to compensate for the heat loss. This offends my sense of efficiency.
Enter, the heat exchanger!! Theoretically, an air heat exchanger should perform a dual function in this use case. Remove water filled warm air from van, use it to heat incoming fresh drier air, save energy and fight mould. All this thing.
I found a chap had been working on a similar idea for a home made exchanger for a chilly flat. Someone else has done a lot of the work?? Get in.
Overengineering is for Winners
Whilst his design seems a good start for my needs, there are definitely some things that I want to add. As this is going in the van, I need some wifi capability if I want to log the data nicely, so I’m using a Wemos Mini Pro as the base board for the project. This is a fantastic wee ESP8266 board that does wifi, talks arduino, and is basically made of pixie dust and wizardry.
Firstly, I’ll have to make adapters for the air inputs, because I printed the parts before realising I have 100mm air intakes with 54mm on the exchanger. no big deal, but won’t be as lovely.
Secondly, I want to track humidity as well as temperature. For this purpose I purchased some DHT11 sensors.. and then promptly discovered that they are a bit rubbish, only do 1 degree granularity and apparently break in about two years of use max (I broke one already). I’ve ordered some BME280 sensors to swap in.
Note: The BME280 sensors arrived, and can only be set to one of two I2C addresses. This is problematic – without multiplexing them, I don’t have enough IO to talk to them over SPI. I have compromised for the sake of expedience and ordered some DHT22 sensors. Slightly less crap than the DHT11s, they have the advantage of being a straight swap with one tiny code change.
Third, I want to drive the fans automatically based on the sensor readings, and for this I’m using TIP120 Darlington Transistors to drive the 12v fans from the 3.3/5v board..
Fourth, I want some feedback. A related requirement is that I want some dimmer lighting for chilling with – the lighting I have currently is very efficient and bright and not terribly relaxing. So, I’m adding a small string of RGB LEDs to the board.
Pop on a couple of switches and we’re getting pretty maxed out on the IO. No matter, I think we’re done!
Lastly.. it’s not quite MaD sCiEnCe looking enough, is it? I think we can do better. I think we can.
Assembling the main body of the heat exchanger was .. a little frustrating. After a few incidents – the last of which resulted in me staring into space and counting to a billion – I worked out a moderately efficient method using a bit of pole (and glueing the pox ridden ends on the tube. Most of a hackspace evening went on this, up to a gritted teeth finish at midnight when everyone was packing up around me..
The code also controls a string of 6 LEDs, to provide a bit of calmer ambient light than the insanely bright overheads I installed. The lights flash red (off), blue (auto) and green (on) to show the fan status. Currently, auto just turns the fans on if the temperature or humidity in the van are high. At some point I will refine this to reflect the outside temperature etc.
There are a number of issues with the design that don’t really mesh with being in a van – the ends are not easily attached firmly to the tube, the air intake/exhaust ports are designed for small 6cm fans – and my ducts are 10cm. At some point I’d like to redesign so as to eliminate all the mad flexible ducting and jerry rigged plywood fan holders – but I want to have it running for a while to see how it performs as is. I still need to make a nice switch panel, sort out the internal air intakes and tidy the wiring a bit for this iteration, in any case.
Extreme hiatus! blog resumes.. maybe.
After a few ridiculous DIYing in campsites/laybys/on beaches episodes whilst travelling, I managed to get everything _pretty much_ working, although with a definite air of redneck chic thereifixedit.com action.
One of the most bodged things was the water tank. The tank itself (40l stainless steel from jay wolfe metal work) was good. The water filter and tap (from pozzani pure water, the Kitchen Spring RIX250 System) also, flawless.
Things that were not so good..
- Filling was extremely awkward and invariably resulted in a little bit of spillage
- The pump has a pressure switch. This means that if the tank runs out, OR if you are on rough ground, an airlock in the system will cause the pump to never turn off.
- There is no inline switch to isolate the pump (see above)
- The wooden cabinet is completely unfinished and thus less waterproofand more.. spongelike.
- One of the plumbing fittings I made in a french campsite eventually came apart 5 months later and the pump pissed water everywhere before I could stop the van and get to the main power isolation switch.
Resulting in the following scenes of mouldy destruction…
I bought a caravan type locking water filler with overflow from ebay, and very bravely fitted it…
Naturally, it rained as soon as I cut the hole, so I drove around for a day with a piece of sushi rice packet taped over the hole, waiting for the anti corrosion paint to cure..
Extreme vinegar and teatree anti mould attack, and a fan heater on in the van for a day sorted the mould out.
Then, four coats of random eggshell later, and the tank is refitted with a proper filler, a switch that importantly can be reached from the driver’s seat, and the tank is optimised for use!
..finger painting is the new emojispeak?
Day 25 being a write off thanks to foam offgassing poison migraine doom, days 26-28 contained frantic ply lining, electrics pre-wiring and the installation of vents.
These little marvels work fantastically well for reducing squeaks etc.. If you get them lined up perfectly. And they don’t jump out of their hole before they are tightened down.. And the bolt is long enough to catch the thread.. In other words, potentially great, but extremely time consuming. Persisted much longer than I should have before swapping to self tapping screws.
Vague attempts to work out cable runs were mostly fairly successful, but the rat’s nest stage was a complete pain in the arse.
I may not make it onto the conver of Practical Woodworking with my box making techniques, but they totally boxed good.
Drilling the giant holes in the van was scary. I made Pep do the second one. I was too scared.
Replaced the AC transformers for the LED panels with some wee 4x1W 280mA DC constant current transformers. It totally worked! Am mad wizard.
Next step.. tidily wire up fuse box and label neatly. Remember fuse box must be dismantled for fitting onto the ply lining. Swear gently.
I made lights happen! aww yeahhhhh.
Luckily, I was carrying the bundle of wires, switches and power outlets I had soldered together ready to fit for the power outlets in the back of the van up the garden as I was pondering how switches even WORK I mean they don’t even make sense. The reason being – how I had done them made no sense. Don’t drive your life hypoglycaemic if you can at all help it is the moral of this story.
Originally, I was planning to make my own ‘rock and roll’ bed, because 1. welding is fun and 2. much cheapness.
After a trip to Swanage, we discovered that attempting to sleep in the frankly victorian level comforts of the passenger bench seat is pretty impossible. The new plan is to get a single seat to replace the 2 bench seats, and get a proper M1 tested rock and roll bed with seatbelts for two. Then I can carry 4 people (and also holy shit I don’t have time to make it myself now agghhhh etc etc).
Yesterday involved a bit of drama, where I discovered that using the cargo area lights continually for two long evenings, along with the radio and charging an iphone.. flattens the battery. A million thanks to Tom for stopping by on the way home from work to help me jump start it..
This caused a logistical problem. I was scheduled to go and get the nice cheaty CNCed ply lining between 2 and 4, and then have time to fit at least the floor in the evening. Engage PLAN B.
Drive to Bletchley, pick up ply from MK Ply Lining
Drive to Northampton, um and ahh over water tank at Jay Wolfe Metalworking, then loose fit ply and carpet in their car park.
Drive to Sheffield to get bed fitted by JDS Metaltech
Not in plan: discover am very sensitive to the new foam supplied by JDS. Get massive headache. Have to look for special snowflake all natural alternative. Burn more money.
It turns out, the cold is actually a good thing for applying Thermoliner. In the event that it is warmer than about 14 degrees, the backing glue sticks like poo to a blanket and any hope of repositioning your unwieldy piece of insulation is doomed.
Have achieved “1960s space shuttle” decor level.
I have also developed a new party trick which consists of fumbling a stanley knife, Charlie Chaplin style, and then continuing onwards to impale my thumb(s) upside down. It’s pretty impressive and I challenge anyone to try and recreate it. (Do not try this at home)
I now have ten days to complete the van before I leave. This is my reaction to clients asking me to do any work in the time before I get going..
The fitting of the leisure batteries and Sterling 50A battery to battery charger.
This charger was a bit more expensive than the standard split, voltage sensitive charger. It manages the charging curve and will charge the batteries to 100%, rather than the 80% managed by standard chargers. It also handles the Euro5 alternator output better.
A friend with more understanding of high current fun than me actually did the work here, I mostly just held things and fretted about deadlines.
TO WALES! Fey can hardly contain her excitement.
The subject of ongoing fights with the dealership, the chairs in the back, have the bolts drilled out and removed. Still need to drop the fuel tank and remove the spreader plates and nuts – but maybe not when there is 60kg of fuel in it..
It rained. Obv.
Fey got annoyed with Molly standing on her so came to supervise..
Days 3-15 contained very little progress. The van turned out to have not been terribly thoroughly checked over by the dealership I bought it from, and as a result I had to take it in to my local garage for what was supposed to be a day, and turned into nearly a week….
I did experiment with some quilting for upholstery:
Fey was less than impressed with the fiesta the garage gave me as a loaner.
I then went a bit mad and made pickles, tonic syrup, hand cream and furniture polish..
Well. That didn’t go entirely to plan.
Yesterday’s moderately storming start stuttered to a crawl today. Did a lot of fruitless searching for a replacement passenger seat to swap out for the current bench. Some actual work *horrors* got in the way in the morning, and this afternoon I realised that the van was still pretty filthy and covered in various stuck on bits of sealant, weird velcro etc etc. After cleaning it all up and removing clingons, I got the thermoliner out and set to trying to make it fit.
I tried a bit more.
Some wrestling occurred.
Lightbulb moment: “it is cold”.
Warmed up thermoliner. Thermoliner stopped doing a fantastic impression of an overtired child resisting pajamas and became a little more pliable. Decided to come back to this job on a warmer day.
Cooked a chicken. Spent the rest of the evening telling Fey the Chicken Smell Drunk Lunatic that it is ‘Not Done’ ‘Not for You’ ‘All Gone’. She didn’t believe me.
DAY 2: END.