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Faster heater anyone?

Dave 2000

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Unsure if this has been posted on the forum before but it may be of interest?

Yesterday I was working on a Renault van, whilst looking around under the bonnet I noticed a device in the heater inlet hose. It is basically a small alloy block that held four diesel engine glow plugs. Anyone familiar with these know these plugs glow virtually white hot within a few seconds, their placement in the heater hose means the water inlet is being heated immediately the engine is started.

I know these systems have been around for years but most are mains powered or there are the Webasto systems, so plumbing into the fuel line, this device is a simple DIY fit. The hose size appears to be similar to the 80, it would take just a minute to fit, cut out about three inches of hose, fit with a couple of jubilee clips. Wiring very straightforward, if I were to fit one in mine I would fit a 'push to make, release to break' or 'momentary' switch, perhaps the headlamp wash button and it could trigger a timer? I would not necessarily use a proper glow plug timer, the amount of time old style versions are on it would not work, modern diesel timers are too complicated with 'on time' dictated by the ECU, many factors decide whether they are to be on for 30 seconds or even half an hour, some coming on to help heat the particle filters, perhaps after you have been driving for an hour or so! IMO the best way to go is a an adjustable 12v timer triggering a relay, if you cannot get a timer to handle around 40 amps then use a light duty version to trigger a heavier relay to power the heater block. That means very basic wiring to be done and the whole project could probably be done in a couple of hours?

No other modifications would need to be made to the vehicle wiring or systems, the charging system for example, even the stock 80 amp unit could handle the 32 amps the four plugs draw, if you have an updated alternator then you could use higher amperage plugs for even quicker heating, but they might not be necessary, the heater device (8 amp plugs) was too hot to touch within a minute of starting the engine from cold, I was inland so it was only about 7°C.

For me the interest was warmer water for my already installed shower system, so just throwing it out there as you guys are getting hit with the cold at the moment .

Regards

Dave
 

StarCruiser

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Interesting thought Dave, glowplugs are easily replaced and designed to work in harsh environments. Might be worth a go. I first thought you meant they were in the airflow to the screen but you mean they are in the water?

I can get ally blocks machined no trouble.
I'll give this some thought.
 

Firewout

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I can get ally blocks machined no trouble.
I'll give this some thought.
just thinking .....you could add a tc probe and a thermoswitch to switch it on and off. or even fancier with a thermostat with ssr output and a big ssr that pulses the glowplugs to regulate the temperature to your liking.
 

StarCruiser

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It can all be done Wout. My only concern is drawing heavy currents for long periods on the battery and charging system but there's going to be ways and means of dealing with that if necessary.
 

Firewout

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I was thinking about some sort of 'flow through afterheater' for a shower to give the watertemp an extra boost when it comes out of the shower system. Piggybacked on the showerpumpswitch. So when showering 'economically' I was thinking of heating times of less than 10'. best to have the engine on when showering.
 

Dave 2000

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Interesting thought Dave, glowplugs are easily replaced and designed to work in harsh environments. Might be worth a go. I first thought you meant they were in the airflow to the screen but you mean they are in the water?

I can get ally blocks machined no trouble.
I'll give this some thought.

Yes the alloy block is inserted in the hose going into the heater, pretty much in the same way as the stock heater temprature control valve, glow plug ends are submerged in the coolant, having antifreeze means no corrosion. Having a block machined to spec would be good.

It can all be done Wout. My only concern is drawing heavy currents for long periods on the battery and charging system but there's going to be ways and means of dealing with that if necessary.

The stock glow plug system on the 80 pulls around 45 - 50 amps but only for a short time, the 4 plugs would pull around 30 amps, it sounds a lot but it would be like a typical owner leaving all his lights on for the five minutes with the engjne off, and that would be on one battery, the 80 with two woukd cover the load no problem.

I was thinking about some sort of 'flow through afterheater' for a shower to give the watertemp an extra boost when it comes out of the shower system. Piggybacked on the showerpumpswitch. So when showering 'economically' I was thinking of heating times of less than 10'. best to have the engine on when showering.

I used to have a hot water tap with resovoir in a mobile workshop years ago however, it relied on the engine having been run for about an hour, it worked in the same way as the indirect coil used in many homes.

This glow plug system could be put in the line from the pump to the shower head, temp control could be as simple as the power shower system, switch on say two glow plugs or four.

I liked the idea based on how simple it would be to install, you could add a recirculating coil with a small pump, the water would be heated as you drove but would be cold by the morning, this method OTOH gives heat straight away.

Regards

Dave
 
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Dave 2000

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Just having a mooch about and see the Vivaro van has the same system, it shares the Renault platform so makes sense, also found this pic.

243283819_1.jpg


Regards

Dave
 

Towpack

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I guess the cheapest route would be to source the bits from a scrap Renault/Vivaro. The only down side to this that I can see is that the engine has to be running as opposed to the Webasto/Eiberspacher solution which doesn't require this. On cost alone though it's a clear winner several times over.
 

Dave 2000

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I did see some varieties of these 'heater boosters' on ebay, and they were as little as £16.00, so yes a breakers yard makes sense, even in terms of testing. I did see one for a Mondeo with just three glow plugs, unsure how good that would be but it would bring consumption down to around 24 amps?

Keeping in mind I have an all 12v setup capable of 200 amps per hour, I would be happy taking a 5 minutes warm shower without the engine running, I have to agree a Webasto unit would be the ultimate. Years ago I planned to pipe warm air up to the tent from one as I really do feel the cold at night, but decided I am not that feeble.......well not yet, no doubt on extra chilly nights I can borrow an extra blanket from @froggy Steve and Dawn :dance:

Regards

Dave
 
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Ben Stratford

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Now Ive seen the picture Dave it does look promising and quite compact. Do you know the temp gain vs flowrate it could achieve?
 

froggy Steve

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I did see some varieties of these 'heater boosters' on ebay, and they were as little as £16.00, so yes a breakers yard makes sense, even in terms of testing. I did see one for a Mondeo with just three glow plugs, unsure how good that would be but it would bring consumption down to around 24 amps?

Keeping in mind I have an all 12v setup capable of 200 amps per hour, I would be happy taking a 5 minutes warm shower without the engine running, I have to agree a Webasto unit would be the ultimate. Years ago I planned to pipe warm air up to the tent from one as I really do feel the cold at night, but decided I am not that feeble.......well not yet, no doubt on extra chilly nights I can borrow an extra blanket from @froggy Steve and Dawn :dance:

Regards

Dave
Mate, you can use out Tigey fleece blanky anytime you want :) - I am very interested in this thread for reason that will become apparent very soon. :)
 

StarCruiser

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Now Ive seen the picture Dave it does look promising and quite compact. Do you know the temp gain vs flowrate it could achieve?
Watts = volts x amps. 8A x 12v = 96watts per glowplug. The average good instantaneous home electric shower is 10,000 watts. A basic electric dribble shower would need 3000 watts (30 heater plugs) and be only just acceptable. What would be needed is to repeatedly pass the water past the heater plugs and store it or have a big can with heater plugs round the outside. Or just buy a 12v immersion heater like one of these https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.co.uk/ulk/itm/183041032159
 

Ben Stratford

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For now i will stick with the jerry can near the fire approach, but one day a circulation system may be an idea to persue. Was thinking about some kind of heat exchanger linked to the exhaust too but as you point out, there are bound to be easier and cheaper ways to heat water.
The immersion heater would need a few amps 600/12 = 50? So feasible for a quick shower but would need constant quite fast flowrate i assume.
The glowplugs would probably be more manageable and flexible using a circulation pump with the plugs in the return loop until the desired temp is achieved. Perhaps a roof mounted black tank could absorb some heat first?
 

Dave 2000

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Watts = volts x amps. 8A x 12v = 96watts per glowplug. The average good instantaneous home electric shower is 10,000 watts. A basic electric dribble shower would need 3000 watts (30 heater plugs) and be only just acceptable. What would be needed is to repeatedly pass the water past the heater plugs and store it or have a big can with heater plugs round the outside. Or just buy a 12v immersion heater like one of these https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.co.uk/ulk/itm/183041032159

Perhaps the heater plugs have a higher rating? The flow is definitely less than a house system so that would help, I do know I could not keep my hand on the device body without losing a layer of skin.

As my shower is already plumbed and works great, if I get five minutes I will plug one of these in and try it, nothing to lose, might be surprised?

Regards

Dave
 

Dave 2000

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Continued research shows the Mondeo has one of these devices, it is a slimmer more compact version and has just three glow plugs but (there's always a but right?), each plug is rated at 250 watts! So @StarCruiser may be right here if the flow cannot be controlled it may be a waste of time?

The three plugs together would pull 60+ amps, so perhaps a shower with the engine running may be necessary?

More research to follow, testing should be done within the next two or three weeks, mainly because it will be at it's coldest here then.

Regards

Dave
 

StarCruiser

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If you need instantaneous hot water you have to have lots of power for a short period (length of shower) and to restrict the shower flow to help raise the temperature. Now, restricting the water, up to a point, is going to be good, however, I would favour a garden sprayer style of head that you have to hold for flow. This would restrict the amount of water used (which is good) but would stop and start the slug of water in the body of the heater which would result in blisteringly hot water for a second or two then luke warm after that. The best way to do a shower is to heat the water over a longer period of time in a small vessel that would hold enough for a shower. Or, if you've got to run the engine, use the waste heat to either heat water in a cylinder or use a heat exchanger to heat the water instantaneously which would then require some sort of flow control to regulate the water temperature but again that would be no good with an on/off shower head. All routes for me lead back to water storage heating. Ebay had some very neat water storage cylinders with heat exchange loops and heating elements but they don't seem to have any more on there ATM.
 
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IRLGW

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I really like this idea but can any vivaro/traffic/primastar drivers out there comment on how useful they are? I imagine it is setup on a timed relay. I think a bench test is in order first...Dave you started it so off you go.

p.s I think if you look at the vivaro door hinges they say Renault on them lol
 

Dave 2000

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If you need instantaneous hot water you have to have lots of power for a short period (length of shower) and to restrict the shower flow to help raise the temperature. Now, restricting the water, up to a point, is going to be good, however, I would favour a garden sprayer style of head that you have to hold for flow. This would restrict the amount of water used (which is good) but would stop and start the slug of water in the body of the heater which would result in blisteringly hot water for a second or two then luke warm after that. The best way to do a shower is to heat the water over a longer period of time in a small vessel that would hold enough for a shower. Or, if you've got to run the engine, use the waste heat to either heat water in a cylinder or use a heat exchanger to heat the water instantaneously which would then require some sort of flow control to regulate the water temperature but again that would be no good with an on/off shower head. All routes for me lead back to water storage heating. Ebay had some very neat water storage cylinders with heat exchange loops and heating elements but they don't seem to have any more on there ATM.

The shower head on my present system is small enough to not kill the water supply, and temp control by powering individual plugs. I think as long as you can take the chill off the water the tougher camper can handle it. The main advantage here is the simplicity of the install, even the wiring.

There are a shed load of ideas and options going around in the grey matter at the moment, one of the thoughts is to have a valve that can redirect the water back into the tank after it has passed through the heater. A few minutes later and the water would be warm enough to take a shower, just change the valve direction, you then have the option to allow the heater to stay on or switch off.

Some camping showers have a switch on the shower head to control the pump on and off, no reason not to wire it into the heater as well. Mine has a pressure switch, turn the tap and the pump runs, stop the water and the pump switches off.

I really like this idea but can any vivaro/traffic/primastar drivers out there comment on how useful they are? I imagine it is setup on a timed relay. I think a bench test is in order first...Dave you started it so off you go.

p.s I think if you look at the vivaro door hinges they say Renault on them lol

Yep Vivaro and Renault the same platform, years back it was Ren Master and Vaux Movano.

I did not look too close at the setup but a couple of things were noted. The heaters did not come on at ignition, the alternator has to be charging which makes sense.

The other thing is it is difficult to get over just how bloody hot this thing gets, as mentioned earlier. In typical cold mode engine thermostat is shut so the water is coming from the cooling jacket through the heater device and into the heater matrix, the outlet was obviously cooler but had some warmth in it all the same and returns this to the block. The water cominng into the device was still bloody cold but the heater was definitely warm. Given diesels take ages to warm up if started from cold and driven straight into traffic it can only be an improvement to your comfort, this not a need for me, just the shower temp.

Whether it is controlled by a sensor or timer I do not know, without a doubt a load that would not be welcome for hours on end again, not something that would be in my requirement but aeasil timed system very easy to do.

Something else, think about the fuel heater in the filter head of diesel 80's, it is basically the same idea, it is fitted and yet it is never thought about, it just does it's thing when needed.

I will be testing this very soon on the shower, others interested in the heater efficiency should just bolt one in and fit a timer, a couple of hours and job done.

Regards

Dave
 

StarCruiser

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Two things you have to think about. Scalding by hot water and legionella growth by tepid (less than 60 degrees) water.
 
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