cast iron radiator cooling

[bschwartz]

Never sure which category to put things in.......

I am planning to use a cast iron radiator in my living room.  Who has used one for cooling, and how do I know how big a radiator I need?

Bigger is better normally works, but space is an issue here, so I was wondering if anyone has figured out a way to calculate minimum sizing.

Thanks.

-Brett

[vdubnut62]

I don't have a clue how to calculate size, but how do you plan to handle the condensate from what will effectively be the evaporator?
Ron

[quinnf]

I am planning to use a cast iron radiator in my living room.  Who has used one for cooling, and how do I know how big a radiator I need?

[snip]

A good place to start might be the surface area of a standard 55-gallon drum (U.K. 44 gallon drum).  In their manuals, Lister specified the use of that size drum for cooling.

Dimensions are:  23" diameter x 35" high.  Surface area (pi * r^2 x height) is 15,180 sq. inches.  You can estimate the surface area of your cast iron radiator by assuming the vertical fins are cylinders and calculate the area that way.  You will underestimate the area by 25% or more, so that should provide a safe estimate.

Quinn

[bschwartz]

Maybe (OK probably) I wasn't clear.

The cast iron radiator will be giving off heat.
It will act as a radiator for the engine using it's coolant.

There shouldn't be any condensate from a radiator over 100 degrees.

When I asked about using one for cooling, I meant cooling the engine.

[bschwartz]

Thanks Quinn!  That makes sense.  Just the kind of thinking I needed.

[mobile_bob]

Quinn:

doesn't that equation calculate volume in cubic inches, and not surface area?

shouldn't it be (diameter x pi) x height = surface area in square inches?

i suppose that doesn't account for the bottom and top surfaces either, so
maybe you add  2 x (pi x radius squared) to the above? to get total surface area?

or maybe one discounts the top surface because the water does not contact that surface?

bunch of square inches in any event

bob g

[Crofter]

I will see if I can find how much heat a cast iron rad will dissipate per square foot area at a given temperature. I am sure you would be able to google it. Bottom line is that if the engine is producing more BTU into the coolant than the radiator can dissipate the temperature will rise above boiling. At this point it starts to dissipate energy by the evaporation of water in addition to radiation. It takes many times more energy to evaporate a pound of water than it does to raise its temperature from freezing to boilling. Most of the open barrel setups were epected to go into this mode but coolant makeup has to be provided for while keeping the level above where it will still thermosiphon. Actual boil off is very effective at dissipating heat but then you have to deal with its results.

If your radiator temperature is above 140 F you would have to guard it and if it is not large enough to keep the engine below boiling you have to provide for steam escape. If you could arrange to have the rad blown with a fan then it will easily dissipate much more heat than simply radiating with only convection air around it.

I would assume that it might eventually boil on continuous engine running heavy load so would have to be used in combination with some additional cooling arrangement. As Ron suggests, if it is actually boiling you will have steam and condensate to contend with! How do you spell sauna?

[bschwartz]

Hmmmm.......

A thought just came to me.
Install the radiator in a loop paralleled with a second normally unused radiator (of some sort) that is only opened if the temp in the primary radiator goes above a set safe temp.

That would allow the maximum temperature to be extracted into the living space, but if it can't cool the engine enough, the second loop opens to provide additional cooling.

[LowGear]

I even shopped for an old fashioned striking radiator.  Then I remembered I run my hot water heat system at about 130 degrees F. and the radiators do have guards on them for safety and disguise.   Steam heat has the evaporators.  Hot water heat does not.

bschwartz has a great, not quite as simple, but great idea as the water wouldn't be coming directly back to the engine at a "too" low temperature for best engine operation.  One of those hot water circulaters would work just fine but they do use some 120 AC.

Casey

[SHIPCHIEF]

You probably won't be running the Lister in the house, so there will be some distance from the engine to the radiator. Heat will be lost along the way, even if it is well insulated.
You will need a fractional horsepower circulating pump too. Like a Grunfos or Taco.
You could run the engine cooling water into a barrel and back to the engine the traditional way, and run an isolated secondary loop from the barrel to the iron radiator with it's own circ pump. You could control the temp of the circ water by shielding the heat absorbtion pipe inside the engine cooling barrel.
You can control the heat of the engine by putting a blanket around the barrel so more heat goes to the secondary loop when weather is cold.
Sounds like a lot of work. Would be a fun project.

[quinnf]

Quinn:

doesn't that equation calculate volume in cubic inches, and not surface area?

shouldn't it be (diameter x pi) x height = surface area in square inches?
bob g

Bob,

I guess I ought to give up offering help here.  I was in a hurry, trying to do two things at once, and you're right.  It's area of the top + area of the side.  Area of top is pi r ^2.  Area of sides is circumference of top X height.  So that's 2945 square inches.

Thanks for keeping me honest.  Now back to work.

q.

[mobile_bob]

Quinn, don't give up!

after i posted, i went to look it up myself and although my method will get you there, it is not the classical method used

apparently they use  (2 x pi x radius x height) + (2 x radius squared x pi)
the first half is basically (dia x pi x height) and the second half relates to the ends

the discussion was good in that it made me go look it up for sure, and i learned the proper way of doing it.

thanks Quinn

bob g

[Bottleveg]

Hello, and my first post from the UK,
I fitted cast iron radiators in my last home but they were run off a log burner.
I would go for the largest radiator that fits your room, fit a thermostat on the Lister water tank to control a pump and a valve or rad state on the radiator. That way the pump will circulate water at a pre set temperature and you can control the radiator if the room gets too hot. You could also fit an anti boil state to dump excess heat if needed. Or
Fit a room state instead of the rad state, so it will turn the pump off at a set temperature and an anti boil state will turn it back on, just in case.
If you plan to have it working on gravity then you could still fit a pump that would assist flow when the tank got above a certain temperature.
Here is a calculator that may give you a guide but it is based on pressed steel rads.
http://www.homesupply.co.uk/radiator_output_calculator.php

PS, I guess a state on the engine would also be a good idea. 

[mobile_bob]

welcome to our new member from the UK



nice to have a few more of the fine folks from over the pond joining the party

bob g

[bschwartz]

Thanks for all the posts and ideas.  The specifics of calculating the surface area of a radiator of course need to be worked out, but the simple idea to make sure it has at least the same surface area as a 55 gal drum just slipped by me.

I've already got a thermostat in the head, and a force air hydronic heater as the main cooling for the engine now.  I figured adding a secondary circuit for dumping that heat in the house next winter would just be a better use of the waste heat. 

First step will be plumbing all the lines from the workshop over to the house (only about 12 feet (4 meters for the rest of you)), and then into the living room.  I got thinking about this as I was at a customers house and saw 3 small 2foot wide cast radiators rusting in the yard.

Thanks for being here guys!!!