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> Recirculate hot water-completed-pictures added

time2roll
Explorer II
Explorer II
I added a system to circulate hot water. Not really a convenience thing but to use my fair weather trailer in temperatures well below freezing.

I installed an El Sid recirculating pump. This pump is good for potable water and appears to be leak proof. Fairly low amp draw on 12 volts.

I used a Grundfos valve mounted under the bathroom sink for this purpose. These are made for home systems. The vale allows hot water to return through the cold water feed back to the water heater. Valve stops the flow as temperature approaches 95F. My hot and cold pipes run together so the heat should also transfer a bit.

Here is a diagram of my water system:
The freeze up was happening under the bunks area that is not accessible.



Here is the pump:



Grundfos valve mounted against the wall:





Pump is running:



Another angle that shows the hot water pipe connection.
Also shown is my GoPower 300 watt inverter if interested.



Has worked like a charm. Only issue is I prefer not to have the pump run continuous as it makes a bit of a low rumbling noise. So I have added a small 12v relay triggered by the furnace signal wire. The more the furnace runs the more the pump runs. And of course can't hear the pump with the furnace running.

And shame on photobucket for stopping the links in a previous thread.
20 REPLIES 20

GordonThree
Explorer
Explorer
lawrosa wrote:
GordonThree wrote:
What does the group think about something like this?

120mm Radiator Dual Copper (eBay)

The Aquahot unit is a bit rich for my blood, for an experimental setup at least.

I already have a pump, and 120mm fan.

The other thing I struggle with (in my mind), for extra winter heat while boondocking... just thinking out loud here...

Gasoline is MUCH cheaper than propane, at least in Michigan, and it's easier to get a hold of. Run out of propane in the cylinder, need to take time off work next to get the it filled. Run out of gasoline in the gas can, stop at any gas station day or night, weekday or weekend and fill it up.

My generator is quieter than my propane furnace, MUCH quieter.

When boondocking in the winter, the generator runs all the time. If I were not alone, I could curb those hours. While the generator runs, my oil filled heater cycles on and off, drawing 900 watts. I can hear the distant purr of the generator, but it's not like the blasting racket the blower in the furnace makes. When it's very cold, or very windy, the blower comes on anyway, the oil filled can't keep up even if i switch it to 1500 watts.

The water heater is quieter than the furnace or generator. My small circulation pump draws 300mA. A few small fans would draw a similar amount. Not sure what the hwh fuel consumption is? I assume if I take enough BTU's out of the water to heat the coach, will the hwh will have to run continuously... Can an RV water heater run continuously, without suffering damage?

Lastly, I would want to install a separate return line for a hydronic system, which means underbelly removal. Not sure I'm comfortable with that. If I'm pulling the underbelly, I could put in PEX and reflectors, and have underfloor heating in half of the trailer. The other half is covered by the holding tanks. How hard is it to drop the holding tanks, not easy is my guess, but I don't know?


Thats a cooler you linked to. Idont think it will be efficiant..

For one the aquahot rating is for 170f water. I doubt the water heater gets that hot. So reduce the BTU output for say 130f water.

It would be best to get the larger 1h 200..

Im not sure the water heater will run all the time. Its a math calculation and what BTU rating the HWH is.. I think they may be in the 10000 btu range? Not sure.

If your running a generator IMO also have an electric wall mount somewhere for back up.

I was wanting to put this under the dinette.. I have an outlet there and this has an adapter that lets you plug it into that outlet and hang it.

So if I am at a pedestal I can use their electric. Or if running gen to charge batts run this heater for a few hours.

http://www.seabreeze.ca/heaters/ThermoFlo/Thermaflo_SF12TA/thermaflo_sf12ta.html

http://www.seabreeze.ca/pdf/SF10TA_SF12TA_Instruction_Manual_2013.pdf


That's an interesting idea, certainly saves on precious floor space.

The cooler I linked to is the same as the core of the aquahot, just a bit smaller. They sell other configurations, 180mm, 240, 360, etc.

I agree with you on the operating temperature. Maybe 130f at the outlet and how much is lost along the way? I'll have a look in the manual and see if there's a btu listed.
2013 KZ Sportsmen Classic 200, 20 ft TT
2020 RAM 1500, 5.7 4x4, 8 speed

GordonThree
Explorer
Explorer
time2roll wrote:
GordonThree wrote:
When boondocking in the winter, the generator runs all the time. If I were not alone, I could curb those hours. While the generator runs, my oil filled heater cycles on and off, drawing 900 watts.
Heat pump would put twice the BTU into the RV for the same wattage as a resistance heater.
Of course there are limits on outside temps.


Too far north for a heat pump. Talking teens and 20s outside temp.
2013 KZ Sportsmen Classic 200, 20 ft TT
2020 RAM 1500, 5.7 4x4, 8 speed

lawrosa
Explorer
Explorer
better off with a small wave 3 heater. No electric and 3000 BTU is all most will ever need..

Mike L ... N.J.

2006 Silverado ext cab long bed. 3:42 rear. LM7 5.3 motor. 300 hp 350 ft lbs torgue @ 4000 rpms
2018 coachmen Catalina sbx 261bh

time2roll
Explorer II
Explorer II
GordonThree wrote:
When boondocking in the winter, the generator runs all the time. If I were not alone, I could curb those hours. While the generator runs, my oil filled heater cycles on and off, drawing 900 watts.
Heat pump would put twice the BTU into the RV for the same wattage as a resistance heater.
Of course there are limits on outside temps.

lawrosa
Explorer
Explorer
GordonThree wrote:
What does the group think about something like this?

120mm Radiator Dual Copper (eBay)

The Aquahot unit is a bit rich for my blood, for an experimental setup at least.

I already have a pump, and 120mm fan.

The other thing I struggle with (in my mind), for extra winter heat while boondocking... just thinking out loud here...

Gasoline is MUCH cheaper than propane, at least in Michigan, and it's easier to get a hold of. Run out of propane in the cylinder, need to take time off work next to get the it filled. Run out of gasoline in the gas can, stop at any gas station day or night, weekday or weekend and fill it up.

My generator is quieter than my propane furnace, MUCH quieter.

When boondocking in the winter, the generator runs all the time. If I were not alone, I could curb those hours. While the generator runs, my oil filled heater cycles on and off, drawing 900 watts. I can hear the distant purr of the generator, but it's not like the blasting racket the blower in the furnace makes. When it's very cold, or very windy, the blower comes on anyway, the oil filled can't keep up even if i switch it to 1500 watts.

The water heater is quieter than the furnace or generator. My small circulation pump draws 300mA. A few small fans would draw a similar amount. Not sure what the hwh fuel consumption is? I assume if I take enough BTU's out of the water to heat the coach, will the hwh will have to run continuously... Can an RV water heater run continuously, without suffering damage?

Lastly, I would want to install a separate return line for a hydronic system, which means underbelly removal. Not sure I'm comfortable with that. If I'm pulling the underbelly, I could put in PEX and reflectors, and have underfloor heating in half of the trailer. The other half is covered by the holding tanks. How hard is it to drop the holding tanks, not easy is my guess, but I don't know?


Thats a cooler you linked to. Idont think it will be efficiant..

For one the aquahot rating is for 170f water. I doubt the water heater gets that hot. So reduce the BTU output for say 130f water.

It would be best to get the larger 1h 200..

Im not sure the water heater will run all the time. Its a math calculation and what BTU rating the HWH is.. I think they may be in the 10000 btu range? Not sure.

If your running a generator IMO also have an electric wall mount somewhere for back up.

I was wanting to put this under the dinette.. I have an outlet there and this has an adapter that lets you plug it into that outlet and hang it.

So if I am at a pedestal I can use their electric. Or if running gen to charge batts run this heater for a few hours.

http://www.seabreeze.ca/heaters/ThermoFlo/Thermaflo_SF12TA/thermaflo_sf12ta.html

http://www.seabreeze.ca/pdf/SF10TA_SF12TA_Instruction_Manual_2013.pdf
Mike L ... N.J.

2006 Silverado ext cab long bed. 3:42 rear. LM7 5.3 motor. 300 hp 350 ft lbs torgue @ 4000 rpms
2018 coachmen Catalina sbx 261bh

GordonThree
Explorer
Explorer
What does the group think about something like this?

120mm Radiator Dual Copper (eBay)

The Aquahot unit is a bit rich for my blood, for an experimental setup at least.

I already have a pump, and 120mm fan.

The other thing I struggle with (in my mind), for extra winter heat while boondocking... just thinking out loud here...

Gasoline is MUCH cheaper than propane, at least in Michigan, and it's easier to get a hold of. Run out of propane in the cylinder, need to take time off work next to get the it filled. Run out of gasoline in the gas can, stop at any gas station day or night, weekday or weekend and fill it up.

My generator is quieter than my propane furnace, MUCH quieter.

When boondocking in the winter, the generator runs all the time. If I were not alone, I could curb those hours. While the generator runs, my oil filled heater cycles on and off, drawing 900 watts. I can hear the distant purr of the generator, but it's not like the blasting racket the blower in the furnace makes. When it's very cold, or very windy, the blower comes on anyway, the oil filled can't keep up even if i switch it to 1500 watts.

The water heater is quieter than the furnace or generator. My small circulation pump draws 300mA. A few small fans would draw a similar amount. Not sure what the hwh fuel consumption is? I assume if I take enough BTU's out of the water to heat the coach, will the hwh will have to run continuously... Can an RV water heater run continuously, without suffering damage?

Lastly, I would want to install a separate return line for a hydronic system, which means underbelly removal. Not sure I'm comfortable with that. If I'm pulling the underbelly, I could put in PEX and reflectors, and have underfloor heating in half of the trailer. The other half is covered by the holding tanks. How hard is it to drop the holding tanks, not easy is my guess, but I don't know?
2013 KZ Sportsmen Classic 200, 20 ft TT
2020 RAM 1500, 5.7 4x4, 8 speed

lawrosa
Explorer
Explorer
GordonThree wrote:
Is the aquahot drinking water safe?


Its only a copper heat exchanger. Probably silver solder. No different then you homes plumbing..
Mike L ... N.J.

2006 Silverado ext cab long bed. 3:42 rear. LM7 5.3 motor. 300 hp 350 ft lbs torgue @ 4000 rpms
2018 coachmen Catalina sbx 261bh

GordonThree
Explorer
Explorer
Is the aquahot drinking water safe?
2013 KZ Sportsmen Classic 200, 20 ft TT
2020 RAM 1500, 5.7 4x4, 8 speed

lawrosa
Explorer
Explorer
time2roll wrote:
lawrosa wrote:
I was toying to do a hydronic heat set up like that with the water heater and a fan over coil. But the water heaters are too small... Not enough btu's.
I had considered that also. Although I was looking at a baseboard style convection radiator. Found some rated for potable water. The plumbing and placement never got resolved. If I was full time it would have more value and get pushed forward.


Yes I had it planned. Get an aquahot cab heater. series 100 draws .5 amp.

Tied it in with a pump and check valve on the loop to it

http://www.aquahot.com/products/Cab-Heaters-Auxiliary-Heaters/AH-100-Cab-Heater.aspx



Mike L ... N.J.

2006 Silverado ext cab long bed. 3:42 rear. LM7 5.3 motor. 300 hp 350 ft lbs torgue @ 4000 rpms
2018 coachmen Catalina sbx 261bh

time2roll
Explorer II
Explorer II
lawrosa wrote:
I was toying to do a hydronic heat set up like that with the water heater and a fan over coil. But the water heaters are too small... Not enough btu's.
I had considered that also. Although I was looking at a baseboard style convection radiator. Found some rated for potable water. The plumbing and placement never got resolved. If I was full time it would have more value and get pushed forward.

time2roll
Explorer II
Explorer II
lawrosa wrote:
Whats the amp draw on that pump?
Depends on model. IIRC mine is the 10 watt battery model. Calls for a 1 amp fuse. In hindsight I think the smaller PV models would have been fine even if a bit less pumped volume.

http://www.solardirect.com/water_heaters/solar/active/pumps/el_sid/index.html#specs

There are lower cost pumps but these are bullet proof with no shaft seal, brushless motor, no bearings. Looks like the price was increased since I bought mine. They were bronze and now fully stainless steel.

Road-Trekker
Explorer
Explorer
Nice simple solution. I did same thing about a year ago, mine is electronically controlled and fully automatic, the system only activates when hot water reaches a certain set temperature. When you turn the water heater off, the system remains active until water temp drops to a certain point then the system deactivates, so it is a set and forget thing. Lot more pictures here: Automatic Hot Water Recirculation System

The electronic control.
Roadtrek Agile SS: Roadtrek Modifications

GordonThree
Explorer
Explorer
midnightsadie wrote:
hey could you turn that into hot water HEATING system ? so that noisey furnace doesn,t keep me awake? add some fin tubing along the base board.


I'd like to try this. I don't think it would have the BTUs for winter camping but might help on chilly spring/fall nights.

Where I get hung up is running potable water through a radiator / heat exchanger. Unlike a system at a house which has it's own coolant (or water), my RV's re-circulation system is using my drinking water.
2013 KZ Sportsmen Classic 200, 20 ft TT
2020 RAM 1500, 5.7 4x4, 8 speed

midnightsadie
Explorer II
Explorer II
hey could you turn that into hot water HEATING system ? so that noisey furnace doesn,t keep me awake? add some fin tubing along the base board.