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Old 02-17-2024, 08:13 PM   #1
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Diesel water heaters and drinking water?

So I'm haunting Amazon for diesel fueled water heaters.


Does anyone have anything to share about how drinking water safe these chinesium diesel fueled water/coolant heaters are? I don't see the German ones are specified to be safe for drinking water, and Chinese ones are 1/5th the price.


What experiences has anyone had? If you are using diesel fueled water heaters for your potable water, have you ever had your water quality tested?

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Old 02-17-2024, 09:45 PM   #2
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I wouldn't run potable water through these. I would use coolant to use in a heat exchanger.
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Old 02-17-2024, 09:48 PM   #3
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Hi, thank you.

Where have you found such a potable water safe heat exchanger, please?
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Old 02-17-2024, 10:31 PM   #4
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Are you going to drink this water or just bathe in it?
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Old 02-17-2024, 10:43 PM   #5
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Most marine water heaters are of the heat exchanger type and use a coolant loop inside along with an electric element. My main concern with the diesel waters is with cathodic protection. If you use it in a system using coolant for exchange in a water heater then the magnesium anode in the tank gives you cathodic protection.
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Old 02-17-2024, 10:54 PM   #6
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I was thinking of using t for the whole house (bus) supply, cooking and bathing. I found a manufacturer claiming it was all stainless steel, but chinesium, who knows?
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Old 02-17-2024, 10:58 PM   #7
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I have looked at a few of them and they are aluminium. They were designed for heating glycol based coolants as in a block heater or hydronic system.
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Old 02-18-2024, 06:56 AM   #8
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these arent potable water designed heaters... scaling in the heat exchanger i think would also become an issue as you are not running a contionuous loop... I would use a heat exchanger... you will need to pull a ton of heat off wit hthe heat exchanger or have a good amount of coolant as a ballast.. the way these heaters work is a VERY hot heat exchanger primary temperature.. the burn can temp is way up there.. so you need your coolant moving through fast and they ramp up and on shut down the water temp continues to rise pretty good from the residual can heat.. so you need to make sure you arent usijng a small coolant loop that can allow the temp to rise if you arent pulling heat off..



I use a 16kw in my DEV bus and it heats the engine coolant from 60 to 75 degrees C.. it kicks on at 60 and off at 75... i can set the temp lower, but it does not allow me to go higher than 75C.. this is fine for pre warming an engine or using it for space heating with blower forced heaters.. im not sure if that would make an exchanger temp high enoguh for you t oget a good recovery time for domestic water in a small space..



when I installed boilers in buildings and wanted good domestic water heating loops in a customer's home or business.. the boiler needed to have a 180F (82C) water temp at least to get good amount of domestic hot water recovery.. anything less meant a really slow recovery meaning they had to live solely on their tank water until the slow recovery could occur..



in the commercial world to shrink the recovery times and heat exchanger sizes we ran steam...
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Old 02-18-2024, 07:01 AM   #9
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I had to look at one of the companies ive used for heaters in the past.. and apparently VVKB makes a package for this... when I ran a VVKB heater previously (I will say I had issues several years ago with their units not wanting to cold start for me in really cold conditions.. (maybe the yhave fixed that now)... this appears to be a package system designed for space and water heating...



https://www.rvheater.com/products/vv...hpf4TJrKYdnuuU
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Old 02-18-2024, 05:01 PM   #10
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I have ventured towards a

17kw Chinesium diesel water/coolant heater purchase, with an AB brand plate heat exchanger, and several shutoff and check valves, and ZeroPone circulation pumps. Here in the next few months when I get the round TuIt, I'll mention how it goes.


Probably with a water safety test thrown in.


17 kW with anticipated inefficiencies/losses should raise 40gal or 40degF water to 160degF in 1 hour or less.


Thank you all.
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Old 02-24-2024, 04:26 PM   #11
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flow rate and head needed?

The heat exchanger has a flow vs heat difference = BTU table. The diesel heater for coolant seems not to mention it's gpm.


Can anyone guess what gpm and head is required? Feel free to go over, I can always valve it back.


The two taskings are domestic hot water heating and engine coolant heating before start in the winter.
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Old 02-24-2024, 06:30 PM   #12
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problem is most of these diesel heaters come with and expect the system to use the provided pump.. my D&E heaters seem to have inferior pumps that didnt last well.. i rpelaced with a davies craig pump.


from what i can tell they use pumps on the 16kw heaters that are 6-9 GPM.. the rise is 10-15 degrees C on average.. the pumps are circulators so they arent designed to pull high head.. usually in the 3-6 PSI range.. in my system because im running a series-parallel setup I have 2 pumps running at any given time.


I installed a high performance MP100 circulation pump to push more coolant through the system and drop the rise a bit as well as run more head pressure in my supply trunk so it would push through my parallel heat exchangers better.. that pump takes 1 inch lines natively and moves 18 GPM.. the Specs dont give a max head pressure.. they give it in head feet (15 max)..



my reasoning for reducing the rise temp was the fact the heater has a fairly long restart process.. it heats the coolant to a max of 75C (the control allows me to set the temp).. it then drops 15 C fro mthe setpoint before starting back up.. having too much rise meant the unit was essentially always ai na state of cycling.. the glowplug was on so much I was afraid of burnout.. moving more coolant through means my return water temp is higher when the unit shuts down so the off cycle and on cycles tend to be longer...



these D7E heaters, unlike most of the diesel air heaters and 5KW webast TSL-17 , doesnt ramp.. it comes on runs and shuts off.. the webasto TSL-17 and most of the chinese Air heaters have a ramp rate and will operate at lower or higher fire..



D&E claimed they had carboning issues when ramping the water heaters vs doing on / off cycles..





the dual pump setup has workedvery well for me...
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Old 02-24-2024, 06:58 PM   #13
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Thank you cadillackid,

may I ask you if you use it for domestic hot water at all, and which heat exchangers you use?


I am thinking of one of these.


https://www.amazon.com/dp/B073ZN9K7K...lig_dp_it&th=1

"AB Plate Heat Exchanger, 4"x 12" 80 Plates Water To Water Heat Exchanger, Copper/SS316L Stainless Steel Brazed Plate Heat Exchanger For Floor Heating, Water Heating, Snow Melting"


At least one in that series. I am trying to size that and the pump.
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Old 02-25-2024, 07:39 AM   #14
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Quote:
Originally Posted by TaliaDPerkins View Post
may I ask you if you use it for domestic hot water at all, and which heat exchangers you use?


I am thinking of one of these.


https://www.amazon.com/dp/B073ZN9K7K...lig_dp_it&th=1

"AB Plate Heat Exchanger, 4"x 12" 80 Plates Water To Water Heat Exchanger, Copper/SS316L Stainless Steel Brazed Plate Heat Exchanger For Floor Heating, Water Heating, Snow Melting"


At least one in that series. I am trying to size that and the pump.

im using mine to strictly heat coolant.. its valved and pump setup for heating the bus cabin independently of the engine.. or heating the cabin heater loops and the engine.. both my bus coolant heaters are set up in this manner.. one bus is still all seats, and the one with the D&E 16kw is a mobile office rig.. my extent of "camping" is i toss an air mattress on the floor and sometimes carry a thetford cassette toilet that i hang up a curtain around when i need to use it..



I have no water system or shower..
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Old 02-25-2024, 10:37 AM   #15
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Thank you cadillackid,

I am aiming for a comfortable retirement live aboard, so I will have hot water/shower/toilet and most likely laundry capability.
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Old 02-25-2024, 04:05 PM   #16
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Quote:
Originally Posted by TaliaDPerkins View Post
I am aiming for a comfortable retirement live aboard, so I will have hot water/shower/toilet and most likely laundry capability.

alot depends on your hot water lifestyle..



I look at my own home life..


1. my roomate and i both like to take showers at night. while neither of us take particularly long showers, its 2 showers within an hour of each other..


2. I use a top loading washing machine which fills part or a whole tub at a time of often warm or hot water.. so this is a demand on a tank.. a front laoder uses small amounts of water more often separated by some time.. so you have recovery time..


3. my dishwasher runs every other day in the evening.



4. i like to wash my cars in cool weather with warm water so i dont freeze..


so in my home life it made the ,ost sense for me to get a tankless on-demand water heater as my water usage is often heaby all at once then nothing for most of the day..



obvipously bus life isnt the same as home life.. but what you need as far as recovery capacity depends on your water habits..



if you installl a big enough heat echanger and have enough BTU output from your heater you could have on or near on demand service.. if time is your friend then you can use a smaller heat exchanger and have longer recovery.. I dont know much about the liquid-liquid heat exchangers to know what temperature the primary needs to be to get 'X' BTU of heat transfer and how much the differential is and rate of rise etc..



when I worked on boilers with domestic water heating loops in home systems you wanted a minimum of 170-180 on the primary to get a good recovery rate for the tank.. most home boilers could run up to 200 but were rarely set that high... the heat exchangers within the boiler for domestic water were physically pretty large.. most homes ran much larger storage tanks than they would with a standard gas water heater as recovery was alot slower.. a home that would use a 40 gallon water heater often had a 60 gallon storage tank is using a boiler loop for hot water..



again, a bus will be different, im just throwing info out for the grabbing from my experiences of living in a house and how i use hot water..
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Old 02-25-2024, 06:54 PM   #17
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So, there's this commenting rule I'm not allowed right now to thank you with the Thanks button, so, in a comment then, thanks.
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