How to hook up a cast iron radiator

[bschwartz]

OK, I've been guilted (by all you guys  ) into using more of the BTUs from my WVO.  Instead of just generating electricity I am going to try to use the 'waste' engine coolant heat to warm my living room. 

Two questions.
1.  What is the advantage of using a heat exchanger with a second loop vs. just running the coolant to the living room cast iron radiator instead of the standard car type radiator currently next to the engine in the workshop?

2.  I have a cast iron radiator with four 1 1/2" openings  (2 on each side) similar to this:
http://i828.photobucket.com/albums/zz204/brettschwartz/Radiator.jpg?t=1287460232

Where should I connect the hot-in.... cool-out lines?
  hot top left, cool bottom left
  hot top left, cool bottom right
  hot bottom left, cool top left..... you get the idea?

I plan on running the lines from the workshop to the living room (about 45') in 3/4" copper.  I'm most concerned with simplicity with some heat gain, as opposed to maximum heat yield.

Thanks for your thoughts.

[oiler]

ALLWAYS hot in on top, cool out at bottom!!!!!!!!!
In and out can be on the same side, no problem.

[Geno]

I have 2 coolant loops with 2 cast iron rads. A primary loop in the engine room with a heat-ex that transfers heat to the secondary loop that goes to the house. I do not store hot water yet. Both loops have ethylene glycol. I can get it cheap. It doesn't freeze.

I can turn off the loop to the house when I don't need the heat. I have a fan on the primary rad for engine cooling. The rad alone isn't large enough in warm weather.

The primary loop uses thermosiphon and has few failure points to leak.

Oiler is correct about hot going in on top but make sure to put an air bleed on the rad and expansion tank somewhere.

Thanks, Geno

[bschwartz]

I checked into pex, and if I had a lot to do, it is cheaper than copper.  As it is, between the cost of crimping tools, connectors etc, the cost is about on par with copper.  The main issues however is a stretch of about 18 feet along one section in my garage that is in a corner of concrete with no easy way to attach the pipe.  Copper is straight, but a roll of pex wants to curl.  Checking internal diameters, I'd also need to go with 1" pex to equal 3/4" copper.  That brings the cost up as well.

Geno,  your setup looks like what I'll come close to.  HOLY COW PILES!!! I've seen your pics before, but never noticed that you hung a cast iron radiator on the wall!!! That must have been fun  .

Thermosiphon would be nice, but I have limited height to work with, and the bottom radiator hose would be to low.... oh well, the taco circulating pump seems to be working fine.  I'll need to pick up a second pump for the second loop.  That would also make it easier to have a thermostat or at least on off switch in the house.

Next question for the heat exchanger group.  How large an HE do I need?  I'm most familiar with the flat plate units as that's what I've run on my vehicles for fuel.  Are they better, worse, or the same as a shell and tube type?

[LowGear]

I have an apartment with hot water heat - OK hydroponic heat distribution.

Hot in top; Amen.

Air bleed at top of radiator -opposite side from inlet (there are automatic ones).

One pump for all radiators - KISS.

Small lines work fine with pumped coolant.

And what the Hell is wrong with copper?  Polished it really goes nice with black, green or red radiators and is a lot less fragile to moving furniture or children at play.

Some sort of pressure relief system like in an automobile only no pressure cap.  Remember hot stuff expands and Lister styled engines just don't like very much coolant pressure.

While anti-freezes does prevent ice in the lines it also reduces thermal transfer so know your environment and mix accordingly.

Nice looking radiators but I don't think my wife is going for that heated towel bar in the guest bathroom.

Casey

[Geno]

Ronmar knows his heat transfer stuff well. A flat plate is the way to go. There is a guy on ebay, Dudadiesel or something like that. Good prices.

Some of the industrial flat plate exchangers are pretty expensive.  The one I am using is a brazed variety, stainless plates, brazed together with copper in an oven.  Search "brazed flat plate heat exchanger" on ebay  and you will see a lot of these smaller units engineered for domestic heating and lighter industrial applications.  I bought the one I use on my 6/1 from a wood fired boiler vendor for under $100 delivered.  5"x12", 10 plate, about 600 sq/in.  It quite easilly takes 195F engine coolant and delivers 120F domestic water, transfering about 18,000 btu/hr at full engine load...  www.flatplate.com has an online calculator to help you choose an appropriate sized heatex for your application. 

Geno,  your setup looks like what I'll come close to.  HOLY COW PILES!!! I've seen your pics before, but never noticed that you hung a cast iron radiator on the wall!!! That must have been fun  .

A pulley on the ceiling and a rope on the wheeler made it pretty easy.

Thanks, Geno

[bschwartz]

Casey,

I'd be really impressed if you can show me how to use one pump for the primary cooling circuit, and the secondary loop 
I already run an open (no pressure) system with an overflow to handle fluid expansion.  I'll do the same for the secondary loop.
I run antifreeze mix in the primary loop more to raise the boiling temp than for freeze protection.
The secondary loop will need a little antifreeze to prevent the lines from the workshop to the house from freezing. 
They will be insulated and buried, and temps rarely drop below the 20's.

[veggie]

I would love to find one of those cast iron radiators for my shop.
I constantly check local papers and online sales but have not had any luck.
Are there any modern manufacturers of wall radiators? My Google searches have not produced much.

veggie

[LowGear]

Hi Brett,

I may have made an inappropriate assumption.  If you're using a heat exchanger then it is harder.

If not:

[LowGear]

With Heat Exchanger:

Is there some reason you need to pump the water through the heat exchanger?  If you can thermosiphon through the heat exchanger then the room thermostat would just turn the pump on/off that moves the water from the heat exchanger to the house.  The nice thing about a more "closed" system like this is you should get less air infiltration on the radiator side and could have a regulator to the water supply.  Remember a radiator that is at 120 degrees is pretty darn warm to the touch.  And a small fan pushing air across it would really enhance its output.

Casey

[Ronmar]

I only use one pump on mine with a brazed flat plate heatex.  The primary loop is thermosiphon, the secondary loop is pumped.  Brazed flat plate heat exchangers are great.  Not very expensive and thermosiphon beautifully.  Mine has 2.24 SQ/FT of transfer surface and easilly handles the heat from a 6/1 via thermosiphon.  It also had 1" NPT ports so matched up nicely with the 1" plumbing on the 6/1...  The only design consideration you MUST meet is that regardless of the conditions, the heat MUST leave the engine.  Under certain circumstances, the cast radiator might not be able to dissipate enough heat, such as when it is already warm in the house.  In my case, I store the heat, and when the storage is heat saturated, I use a radiator to dissipate the remaining heat before returning the secondary fluid(domestic water) to the heat exchanger.  The emergency backup is to dump hot water from the storage(replaced by cold water) if the rad or fan has issues.

If your cast radiator cannot handle the full heat output 100% of the time, you will need an alternate cooling path.  If I were doing something like you are talking about, I would do it like Geno has done.  The heat exchanger gets first crack at the coolant comming off the cylinder head.  If not enough heat is taken away by the heatex, the engine coolant(primary loop) then flows into an auto radiator with a thermostatically controlled fan.  Radiator temp hits 200F at the top of the radiator, and on comes the fan to handle the situation.  In this way, it makes no difference at all if the secondary loop is in use or not to proper engine temp maintenance.  Kind of like this drawing but with only one heat exchanger above the auto radiator.

[bschwartz]

Ronmar,

I think you pretty much stated the way I will go.
From engine, through heat exchanger, then through thermostat controlled fan/radiator.
Second loop is pumped from heat exchanger to house radiator based on home thermostat/switch to control the secondary pump.

I'd love to plumb the primary radiator/heat exchanger loop like your drawing, but I have a very low height problem as I only have an 8' ceiling in the workshop (I bought the house this way) and to lower the height even more, the garage door hang is right there, so I only have 7' clearance at best.
I have the engine mounted on a concrete base approx. 18" high.  That doesn't give me much room for thermosiphon.  Hmmmm maybe a picture would be in order........
Let me go to the workshop and grab some pixels.

[bschwartz]

http://s828.photobucket.com/albums/zz204/brettschwartz/?action=view&current=IMAG0083.jpg

Not a great picture, but you can see the lower radiator line is level with the lower engine port, the upper radiator line is right near the garage door when it is open.  The large white tube is the intake ported to an air cleaner/silencer in the space above the ceiling.  I initially set it up to thermosiphon, but the combination of 3/4" copper lines, and smallish radiator (actually a hydronic heater) wasn't up to the task at full engine load.  before adding the taco pump, I had an overheat situation that brought the temp 6" from the head on the coolant line at 365 degrees!!!!!  No coolant left in the system as it ALL boiled out!  I didn't have any sensors in place, and didn't know about the problem till my lights started flickering.  WOW was that engine HOT!!!

Anyway, I'll need to figure where to put the FPHE in this system as it sits now.

[LowGear]

Ronmar,

Your's is much much better than mine.  By taking the heating water after the primary radiator makes it much friendlier to humans and pumps.  A heat register at 120 degrees is really warm.

I really missed it when I put the no heat exchanger system with the pump on the hot side.  Like the Buderus in the apartments the pump goes on the cool water return to the boiler or heat exchanger.

A simple AC fan behind my wood stove really changed the amount of heat I got out of a small wood stove we heated the front part of the house with.  We started leaving all the doors open and the house just seemed healthier with the better circulation though out the house.  Fans are good.

Casey

[bschwartz]

Casey brings up a good point.

How many votes for putting the FPHE after the engine radiator?