cast iron radiator ?'s

[NE WOOD BURNER]

so I picked up 9-6 column/tube radiators today.

my thought was to install with new TRV and home run the plumbing.

questions:
1. does it matter if I use bottom ports in bottom as opposed to the top ports as they are currently plumbed?
2. what size piping would be suggested for plumbing in. 1/2" would be desirable.

 

[ewdudley]

1. does it matter if I use bottom ports in bottom as opposed to the top ports as they are currently plumbed?
2. what size piping would be suggested for plumbing in. 1/2" would be desirable.

You can do in the bottom port on one side and out the bottom port on the other, in the top port on one side and out the bottom port on the other side, or in the top on one side and out the bottom on the same side. All three would work well enough. I think in bottom out bottom is as good as any scheme, and is easier and looks better. (I assume there is a passageway all across the top of each radiator, or they won't work at all for hot water.)

If you're only doing one or two radiators on each home run you could go as small as 3/8", pull it like electrical. 1/2" for small home runs could easily be overkill in a lot of cases. Just run the numbers from a PEX pressure drop table, adding three or four feet for each elbow to get a good idea.

[Edit:] Maybe put a few drops of ATF on the plugs you'll be taking out. In a week or so they might walk out without too much trouble.

 

[NE WOOD BURNER]

yeah bottom is what I've seen. these are in top out top. thought it was odd. I want to do in bottom out bottom

 

[NE WOOD BURNER]

These radiators are for water. just put my eyes on them. they enter top and exit bottom. they are 23" high and 6 tubes. the largest is 17 sections. so I'm calculating about 245btu/hr per section @130 degree water 4165 btu/hr out of the 17 section radiator based on 70degree room temp.does this sound about right?
glad to hear 1/2" pex would work that does make running the feed and return a breeze.
any suggestions on a trv brand and style?

 

[Seasoned Oak]

Iv seen these run with 3/4 but i dont think its necessary to go that big. Back before we had electric pumps on them it was but not anymore.

 

[NE WOOD BURNER]

these have 3/4 and 1 inch on them now. these where installed in home that was early 1800 poor insulation much bigger than mine. im sure @ high temps they are more than adequate.

 

[salecker]

I'm installing mine top in and bottom out.I'v used 1/2 inch runs.I read that 1/2 run output up to 15000 btu's.I'm installing up to 20 tubes per run.I used Danfos TRV's not real pretty but easy to get.I have an Alhpa pump supplying my manifold.
Thomas

 

[Jeff S]

ewdudley is spot on as far as connections and pex sizing,

My own system consist of 4 homeruns with 2 rads each using 1/2" pex on all bottom connections.I was fortunate with my system that I had access to several rads of various sizes to choose from,after doing heat losses for every room I used the appropriate rad for each room and never had to use any trv's.House varies less than a degree one end to the other.

 

[NE WOOD BURNER]

Jeffs: what was your design temp for your supply water?
Im trying to size for 130

 

[Jeff S]

I was originally shooting for 140 but have found that I rarely need over 115 and never over 125,at first I experimented with out door reset with temps as low as 90 but now I just set supply temps at 115 and if we get int to a long spell of cold weather I will adjust it up to 125 but at these temps you don't want to try and setback at night just constant temps ,in my case 72*

 

[NE WOOD BURNER]

I used the appropriate rad for each room and never had to use any trv's.House varies less than a degree one end to the other.

this is where im at right now finding appropriate rad for each room. how many sections of rad did you end up with in your rooms?

I was thinking trvs for the weekend days when im @ a higher water temp. how do you control your temp? do you use a central thermostat?

 

[Jeff S]

How many sections is just part of the equation,You need to know much EDR(Equivilent Direct Radiation) for each rad is.
How many sections ?
How many tubes per section?
How tall?
How wide?
Tube or column? (How many inches center to center of each section ?)

 

[NE WOOD BURNER]

these are 23" tall 6 tube 9" wide I have a variaety from 3 sections to 17 sections. I get 3.50 edr for each section. @ 140 degrees I would have 315 btu/hr of each section. so you designed @ 140 water temp and its working well at the lower temps?

 

[Jeff S]

Cast Iron Radiators are an under appreciated low temp heat emitter.

If memory serves me right I used 0* outside as part of the equation,not knowing that the average winter temp in my area is around 30* and these rads do a great job with swinging temps.This is the first year in for that I didn't use 115* water because we had so many days below 0*,when the house fell to 70* I raised the incoming temp to 130* witch is actually overkill it is set back to 115* and doing fine.One of the advantages of using these low temps besides less standby losses is that you can sit on them to warm your behind with out burning yourself.

I used to use a 90,000 BTU forced air gas furnace but with the Rads I calculate that I have never used over 10.000 BTU.s,it amazing how much heating systems are over-sized.

 

[NE WOOD BURNER]

Cast Iron Radiators are an under appreciated low temp heat emitter.

I agree.
I figure its like having a wood stove in each room. im replacing the 90000-113000 fha unit as well. i have a cape basically 4 12x12 rooms down stairs and 2 bedrooms up stairs open to second floor at the entrance. im thinking of using the FHA ductwork as my chase for the plumbing. eventually i will replace the fha furnace with an oil/pellet boiler for when i am really old.
I am just concerned of blowing out to much heat with higher temps. I assume you control the temp by your variable speed pump?

 

[Jeff S]

With your design temp is you talking Supply or average?

Rads are calculated with average temps

170* 150 BTU per EDR ie. 180* supply 160* return.
145* 100BTU per EDR
120* 50 BTU per EDR

TRV,s are probably the best choice if you can't properly size the rads.

 

[Jeff S]

I am controlling my temps with a single speed Taco 007 a digital controlled aquastat(thermopulse)and a 120 volt solenoid valve . The aquastat take a temp reading ahead of the circulator and operates the solenoid valve from my storage tank when valve is on it let some hot water into the loop from the top of storage while returning some to the bottom of storage when the valve is of it only circulates the water in the loop until it cools.

I only use a 1* differential for controlling valve(actual swings are greater and vary depending on storage temps)

could use a zone valve instead of solenoid valve.

 

[Seasoned Oak]

to warm your behind with out burning yourself.

I used to use a 90,000 BTU forced air gas furnace but with the Rads I calculate that I have never used over 10.000 BTU.s,it amazing how much heating systems are over-sized.

I see even some plumbers oversize coal systems by 300-400%. Amazing waste. Downside of this is coal has a minimum feed rate just to keep burning. Make for a very overheated house in spring and fall. My system runs 24/7 on the coldest day of the year. Just about right.

 

[NE WOOD BURNER]

so based on degree days my worst day I will be @ 42300 btu/hr for total house load.
so should I size my radiant for the worst day or will that be overkill?

 

[Seasoned Oak]

so based on degree days my worst day I will be @ 42300 btu/hr for total house load.
so should I size my radiant for the worst day or will that be overkill?

My boiler is 95000 Btus On the coldest night(about Zero Degrees) this year it was maintaining a 75 degrees average in my house. At times it would dip to 73-74. So running 24/7 but maintaining temp pretty well. Id say thats about sized right. Plus in the spring and fall and milder winter weeks i add the domestic hot water load to it as its not taxed anymore to maintain home heat. Anyway i can even buy a smaller boiler if i wanted one,mine is the smallest they make for coal. You may have trouble finding a boiler as low as 42300 depending on the type fuel used.

 

[NE WOOD BURNER]

You may have trouble finding a boiler as low as 42300 depending on the type fuel used.

the idea here is to burn the wood boiler to heat the thermal storage(2000 GALLONS). draw off the storage through the radiators to heat house. For convenience i want to extend time as long as possible before another refire. so currently trying to select the right amount of cast iron radiators to keep house warm with storage temps that can fluctuate 100-180 degrees.

 

[Seasoned Oak]

the idea here is to burn the wood boiler to heat the thermal storage(2000 GALLONS). draw off the storage through the radiators to heat house. For convenience i want to extend time as long as possible before another refire. so currently trying to select the right amount of cast iron radiators to keep house warm with storage temps that can fluctuate 100-180 degrees.

You should be able to use fairly cool water. I would think even as low as 100 Degrees would work with these cast iron radiators to maintain a heated space. One of mine in my finished basement is 6Ft long 2 Ft high and about 8"wide. Its a heat storage machine all in itself.

 

[NE WOOD BURNER]

they do work well for low temp. Im just trying to use the math and make sure i use the correct size radiators to meet my demand. the lower the temp the more surface area is required to maintain a constant temp.

 

[BoilerMan]

I was sold on CI radiators when I was in a house that had them throughout. They were recycled and installed in this house in the late 80s. I was sold, found some of my own and blasted and painted them. Wonderful, truly like having a wood stove in each room.

I'd try w/o the TRVs, you may find that it works well w/o them. Just use water temp to get your heat on the weekends. I did a thread on my CI install this fall.

I see even some plumbers oversize coal systems by 300-400%. Amazing waste.

It's not just coal, I just finished a real heat loss calc for a house I was doing some work in. There were three other contractors that had given this guy a quote on a new FHA furnace. He is going from oil to LPG, all the quotes were for a 120,000 btu/hr condensing unit. One was for a two stage condensing unit still 120MBTU high fire. I did the calc at -40F and came up with 74,970btu/hr design temp. I told him to get a two stage 80Mbtu unit.

He asked me why so small of a unit, and said the other companies said his house needed the larger unit or he would be cold.......... Guess who two of the quotes were from........you guessed it, his friendly gas company. He said none of them measured any room or looked at any insulation in the attic. I figured the place at an R-5 wall and R-20 in ceilng. Walls empty, old house

WOW, and these people call themselves pros

TS