EFM 520 Round Door Vs Square Door?

Why is the square door model more desirable? Is it just an indication of age? Or is the square door somehow functionally better?

And what kind of BTU output is a 520 rated for?

Also, do parts swap? I have a square door, and I was thinking of adding another one for capacity and redundancy. It seems that the round door models are like half the price.

Joe,

On the 520, They started making the square door around 1980 ( I'll let others confirm that). But the big change came around 1962 (I think) when they stopped making the tube boilers and switched to plates. I think you are right about the square doors costing a little more just because they are newer. I also would think the square door units would be easier to clean.

Boilers, bases and stokers are all interchangeable. Some of the stoker parts have changes over the years (gearbox, crank, connecting rod) so be careful when interchanging those parts.

-Don

I do not or ever have owned a EFM but with the experience I have with my VW is the square door will always be my first choice. I have a hard time believing you can really reach up in their with a round door to give it a good brushing like a square door. But again, this isnt a first hand encounter.

Anthony,

I was actually just wondering about the square door and round door Van Werts. When did they change? Did they change anything else on the boiler?

Here is an 800 for sale. It is a round door.
**Broken Link(s) Removed**

-Don

My Grandmother's is round door Van Wert, pot is far less accessible than ours with the square door. With ours you can just light the newspaper, with hers you needed to light a piece on the outside and stick it in there lit. When you are adding the wood you have to kind of take guess, it's pretty far reach. If you were the hulk your arm may not even fit in it.

Other than lighting it i"m not aware of any differences.

joethemechanic wrote:Why is the square door model more desirable? Is it just an indication of age? Or is the square door somehow functionally better?

And what kind of BTU output is a 520 rated for?

Also, do parts swap? I have a square door, and I was thinking of adding another one for capacity and redundancy. It seems that the round door models are like half the price.

I think the rating is 149,000BTU per hour on the 520. That is a little deceiving on a coal boiler though. I don't know what all the math works out to but if you check out this EFM thread by "stokerman" his 520 install is in the EFM boiler building (warehouse).
Installation of a Stoker Boiler at EFM
It is 1 EFM 520 set up to heat the office area as a priority and the rest of the warehouse gets what is "leftover" as he put it. The warehouse is about 60 degrees. He seems to be running the 520 flat out, 10 teeth. He also states in this thread that the existing 400,000 BTU per hour oil boiler could not make the warehouse as warm as the 520.

Shoot Joe, that might be a good option for you to think about for your building. You have a 520, install another 520. Two 520's should heat your building without running flat out.

-Don

Joe, it basically comes down to accessibility of the stoker and difficulty of cleaning. The oldest square door I have seen was a 1980, and all of the square door units have a port on the side for an oil burner...hence the "DF" (dual fuel) in the current model number. I have installed a few of each, and I prefer the square door units because they are easier to clean. With that said, the round door units are usually less expensive. For the right price, I would install another round door unit. My dad's is a 1953 and still runs excellent.

The flip side of the convenience of the big door, the oil burner port and the change in heat exchanger design was a decrease in the heat exchange area. The original A520 had a heat exchange surface of 30.8 sf vs. 28(?) sf for a DF520. All else equal, it may be somewhat more efficient. Beyond the sf difference, some experienced people view the firetube design as being more efficient due to the path followed by the combustion gases.

This doesn't mean that efficiency should override the other considerations; just that there are more trade-offs to consider.

Mike

StokerDon wrote:Anthony,

I was actually just wondering about the square door and round door Van Werts. When did they change? Did they change anything else on the boiler?

Here is an 800 for sale. It is a round door.
**Broken Link(S) Removed**

-Don

That VW 800 is a steal at that price as long as thier aren't any rust holes. I'd prefer square doors but if I needed the ass that 800 would put out, the door style wouldn't be a show stopper IMO.

I think there are other variables that make more difference in coal consumption than the exact design of the 520. The previous owner of my dad's 520 replaced it with a DF520, and said they found no obvious difference in operation or consumption. I imagine any difference would be easier to see at a high feed rate.

Just noticed a nice round door efm in the classifieds: **Broken Link(s) Removed**

As far as efficiency of heat exchanger design, I think Van Wert really schooled EFM in that department. Scottscoaled can speak to his experience of a VA400 vs an EFM 520.

Heat exchange surface area is enough of a factor that it is routinely reported on nameplates and spec sheets. All else equal, 10% more is better than 10% less.

My comments on efficiency attempted to respond to the OP's question about the differences among the different EFM models. Not sure how the VW vs. EFM comparison relates to that. For those of us who have never seen the heat exchanger of a VW400, could you please describe further the design difference(s) you reference?

Thanks.

Mike

Mike, my point was that 10% more surface area does not neccessarily translate into significant or easily measured coal savings, at least not in an average residential application. More is better, but I don't know how much better. At 4-5 teeth I do not think it matters much at all, which was the case in the comparison I mentioned with my dads boiler.

To your point, a Van Wert is irrelevant to the different 520's. If Joe is interested in them, I will dig up some pictures.

StokerDon wrote:

joethemechanic wrote:Why is the square door model more desirable? Is it just an indication of age? Or is the square door somehow functionally better?

And what kind of BTU output is a 520 rated for?

Also, do parts swap? I have a square door, and I was thinking of adding another one for capacity and redundancy. It seems that the round door models are like half the price.

I think the rating is 149,000BTU per hour on the 520. That is a little deceiving on a coal boiler though. I don't know what all the math works out to but if you check out this EFM thread by "stokerman" his 520 install is in the EFM boiler building (warehouse).
Installation of a Stoker Boiler at EFM
It is 1 EFM 520 set up to heat the office area as a priority and the rest of the warehouse gets what is "leftover" as he put it. The warehouse is about 60 degrees. He seems to be running the 520 flat out, 10 teeth. He also states in this thread that the existing 400,000 BTU per hour oil boiler could not make the warehouse as warm as the 520.

Shoot Joe, that might be a good option for you to think about for your building. You have a 520, install another 520. Two 520's should heat your building without running flat out.

-Don

I wonder what the deal is with the BTU ratings. My mother always insisted coal was the best and warmer. But then again she worked for The Badenhausen Div. of Riley Stoker. I always figure a BTU is a BTU but maybe I'm missing some factor.

I really have to get up on my manlift and check the Modines. Well Westinghouse Modines . I have 4 in the building and one Modine modine that is new. I need to check the capacity. Some of the fans run kinda noisy. but I'll check them out and install new bearings in the motors. Probably should meger the stators too while I have them apart. That is if I can figure out what box I packed my megger in.

If I can't find tags on the modines is there any kind of rule of thumb that I can measure the cores and come up with a rough estimate?

joethemechanic wrote: I always figure a BTU is a BTU but maybe I'm missing some factor.

You are not missing anything. Coal systems stay warm, and tend to have a lot of thermal mass...so a house with an EFM in the basement and warm floors will feel warmer than a house with an oil boiler and a cold basement.

If you have modines already installed, a boiler makes a lot of sense for your application. I would measure the cores and compare them to the current offerings from Modine and see what matches up.

Ok here. is what I have

This is the existing EFM





It runs baseboard for about 800 sf of office plus this Modine in the North Bay (welding shop) 4,000 sf 20 ft ceilings



I also have these Westinghouse "modines" in the shop that were connected to a steam boiler that no longer exists.

Three of these



And one of these smaller ones



All total the building is like 9,000 sf

Hey I really did try to upload directly to the NEPA site, but I must be doing something wrong.