Help- Hw Coil Not Working, Have Pics

 
MA_coal_fan
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Post by MA_coal_fan » Mon. Oct. 27, 2008 1:21 pm

Hi all,
I was messaging another member about this.
Basically, I'm not getting any value out of my new hw coil installed on my Harman MkII.
My oil burner still fires as always.
He and I thought that adding a circulator would help a lot.
But I've talked to 2 pros since- my regular heating/boiler guy who installed the setup, and another plumber/heating contractor in town, and they both
say that these things are kind of a joke, that they don't put out enough btus because of size of coil, and that a circulator would be a waste of money.

Let me describe my setup as I did for the other member. See pictures of my setup attached.
I have a 7 year old Weil Mclane WGO Boiler. I have a late 50s ranch with one heating level(first floor).
The boiler has a single zone that goes to all the radiators on the first floor.
Then I have an Amtrol Boilermate indirect water heater connected right off the boiler as a separate zone.

I installed my Hilkoil 18" loop in my Harman MkII.
Then I had my boiler guy, who's generally an ace, pipe the coil into the system.
Now the stove is on a hearth in a separate finished main room of the finished basement. I'd say it is about 15-18ft from boiler to stove. The boiler and boiler mate are in a little adjacent side room.

My guy read the instructions, considered it, and then chose to pipe the stove's coil directly into the WM boiler. He came out the relief valve towards the top left front for one side of loop, and back into drain valve at bottom right front. See pics. He mentioned that going directly to the boilermate would probably require it's own expansion tank, circulator, etc- would be more complicated, expensive, could interfere with normal operation of system, etc. I liked his idea and still do. He came off the stove coil ends with about foot of cast iron pipe, 90 degree cast elbow, then into fosta-pex plastic tubing that are wrapped in foam insulation and run the length on the floor, through wallboard into the boiler. He chose passive, thermo-syphon type method, I think. The work looks great as usual.

Problem is that I don't think I'm getting the benefit of the coil.
I've had the stove fired for 8 days now. The iron pipes get super hot, as you'd expect. I tried unplugging the oil burner lead from the main Honeywell control on the front of the boiler. This allowed the Amtrol to stay on and run it's own circulator when it needed to, but also prevented the burner from coming on, as intended. So what I was hoping for, was that the Amtrol running it's circulator would pull through the boiler water out through the stove loop, get heated, and come back through the boiler, then out to the amtrol tank's own coil to heat the water. I was expecting to see the boiler's temp dial stay up in the right range- 170 degrees or so.

Well, I noticed that when the burner was shut off, the boiler temperature guage dropped way down to it's lowest reading, even when the coal stove was completely fired. I also felt that the piping right at the stove was hot, but if I felt along the pex tubing near the boiler, it was room temp.
Now, when the burner is connected and it fires, it does seem to get boiler up to temp pretty quickly, when the coal stove is running, almost like it's getting boosted by the stove loop. And I can also feel that the pex tubing ends closest to the boiler are pretty warm at this point.

What I am wondering is if I need a small circulator running on the fosta pex coil loop, and placed closest to the boiler drain valve on the bottom right. Maybe this would allow it to continually feed the boiler heated water, and keep it up to temp without need for the burner firing?
Do you think I'll see benefit out of the circulator in this setup?

Thanks,

Brian

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MA_coal_fan
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Post by MA_coal_fan » Mon. Oct. 27, 2008 1:24 pm

Another thing I notice, is that when boiler is fired, you can feel the fosta-pex tubes, along the loop run and they're room temp.
Hot at the boiler end, hot at the coal stove ends, but cold in the middle.
-Brian

 
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WNY
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Post by WNY » Mon. Oct. 27, 2008 2:06 pm

Are you trying to use the stove to supplement the heat in the boiler to use for heating or just DHW (Domestic hot water)?.
The small coil in the coal stove are not even close to producing any amount of heat except for DHW (depending on your usage. Also, they recommend anything over 10' to use a pump, thermosyphon probably wouldn't work.

 
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Blackdiamonddoug
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Post by Blackdiamonddoug » Mon. Oct. 27, 2008 2:12 pm

the pump should be 2 gpm or less any more the water will travel so fast through the coil it won't be able to pick up heat
BDD

 
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LsFarm
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Post by LsFarm » Mon. Oct. 27, 2008 2:13 pm

Are you sure you don't have air trapped in the loop?? Did you purge all air from the system??

I usually tell people when they try to make a stove into a boiler that it won't work, there is just too little surface area being heated in a simple loop.. Just look at the surface area of a boiler,, it is huge,, then the surface area of a coil.. it is tiny in comparrison.. The coils are meant to slowly heat a 40-50 gallong hot water heater over 8-12 hours..

If you are sure you don't have air trapped in the coil, then the only way to get more heat or get some heat will be to put in a small circulator.. but don't be surprised if you are not overly impressed with the heat from a single coil..

Greg L

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MA_coal_fan
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Post by MA_coal_fan » Mon. Oct. 27, 2008 2:22 pm

Thanks for the replies.
I am definitely not trying to heat the whole house forced hot water radiators with the loop. Just DHW.
My guy didn't intend it either. Just chose to tie in this way instead of going directly to into the boiler supply and return pipes out to the boilermate. I like the idea of a slow circulator. Would I want this on the loop end going into drain valve (lower bottom right) on boiler?

 
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Freddy
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Post by Freddy » Mon. Oct. 27, 2008 3:07 pm

From the looks of things you are going a bit too far to have it gravity. Get a bronze pump and hook 'er up. Maybe a ball valve in line to slow the water down? Maybe not. Make sure it can't shut off completely, and make very sure you have a pressure relief valve that can NOT get shut out of the coil. I think your boiler people are a pit pessimistic. You'll heat apile of water cheap this way.


 
MA_coal_fan
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Post by MA_coal_fan » Mon. Oct. 27, 2008 3:50 pm

Thanks, Freddy. I like your attitude! :D
I'm going to give it a shot. What have I got to lose?
I like the Taco circulators. Have two already. Anyone happen to know what model is going to be slow speed, < 2gpm?
I'll check em online.

 
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traderfjp
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Post by traderfjp » Mon. Oct. 27, 2008 4:25 pm

First off the plumber did a butcher job. Do u know any plumbing at all? He should have used brass elbows where the coil comes out of the stove and then piped the lines through the floor. No offense but it really looks bad. You must be single because that setup wouldn't make it with the wife factor. Next,. the coil is too small to pipe into your boiler. You're better off buying a 100.00 HW tank and a circulator and let the coil heat the water in the tank. Why are you running your boiler anyway? With a few valves you could pipe the HW tank into your system. I also don't like the plastic tubing either. I would have used copper but I don't know the melting point of your pipe so.......

I have a 40' custom coil I had fabricated from SS and I have it piped into my boiler and it will help heat my basement. However, I have close to 40' and you have 18" which is not a lot of surface area. And to be honest my coil doesn't do that much when the stove is on idle. I need to be running the stove a bit to get any real heat. Your plumber is now saying the coil is a joke but he didn't advice you before you spent your money. I think you can make it work with a circulator and tank but what you have now is not the best setup.
Last edited by traderfjp on Mon. Oct. 27, 2008 6:50 pm, edited 1 time in total.

 
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LsFarm
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Post by LsFarm » Mon. Oct. 27, 2008 5:08 pm

The most common Taco pump is the 007 if this is what you have use it, just put a ball valve in the loop somewhere and use this valve to choke down the pipe size, and slow the circulation rate.. I think a Taco 007 is about a 12gpm pump.. you would have to use a 004 or smaller to get only 2gpm...

I'm not sure the loop will keep your boiler warm, much less keep up with DHW... but I might be wrong,, especially when you have your fire cranked up.

Greg L
..

 
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Post by Razzler » Mon. Oct. 27, 2008 6:28 pm

Ma coal fan, I put a hilkoil in my Harman SF250 and hooked it in to my EFM oil boiler but couldn't keep the water temp up much past 140*. So I designed my own ciol the hiokoil was 57" long and the one I made was 120" and it still wasn't anuff. I could get the water to 170* but couldn't maintain it to long. Now I install the 57" ciol in as well it was a tite fit but I got it in there and hooked it in sequel for total of 15ft. Now I can heat the boiler and the domestic hot water as well I can maintain between 160* and 180* the only time the oil burner will kickin if there are back to back showers. I have Taco 007 running with a ball valve to slow the water down. Just like Traderfjp said you don't get much heat out of it when the stove is just idleing you have to keep the stove temp up to be any good.

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Post by traderfjp » Mon. Oct. 27, 2008 7:00 pm

I still want to know why he needs to heat the boiler. The boiler mate is great when you're running a boiler to heat your home and it is at 160/180. If he has a coal stove there is no reason to run the boiler and he can use a HW tank instead of an indirect tank like the boilermate. I also found this: PEX tubing is light weight, and it can withstand operating temperatures of up to 200° F (93° C). For a hot water heater I think you would be fine but temps can get high if the water isn't being used.
Last edited by traderfjp on Tue. Oct. 28, 2008 12:14 am, edited 1 time in total.

 
MA_coal_fan
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Post by MA_coal_fan » Mon. Oct. 27, 2008 11:13 pm

Traderfjp, I hate to admit it, but I think you're right on some of your hard hitting points.
The guy that did it is our independent oil boiler man, we've been using for 8-9 years. He is good,( did a nice job putting a new oil tank from outside to in), but I think he put us together a little bit on this one. Ha, you're right he was kinda like no problem before the sale, but then seems to back peddle when results are less than desired. :roll:

But, I'm going to give it a shot with the circulator. The setup is there and intalled, so I'll approach it with a few mods, before I give up totally and go the other route with an isolated direct HW tank attached to the coil. Seems to me if you could continually over several hours circulate hot water through a 40 gallon HW tank, to keep it up to temp with this coil, why couldn't you do the same for a 12 gallon cast iron boiler body that's wrapped in insulation? Remember, that no water is going or bleeding up stairs to the regular radiators since zone is off. And then the boilermate can just sap off some of that water like it always does. I do like the simplicity of his setup. Maybe it won't work, but it's worth a shot.

One thing I do need to get after him for is the pex tubing near the coil ends. It's starting to bubble from the heat.
He should have used copper there. You hit a lot of points dead on. Sounds like you know your stuff.

I would definitely say from my experience, that there is a lot of trial and error, and self-reliance implied in buying one of these coils. They are not a 100% slam dunk.

 
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Post by djackman » Mon. Oct. 27, 2008 11:45 pm

MA_coal_fan wrote: One thing I do need to get after him for is the pex tubing near the coil ends. It's starting to bubble from the heat.

Circulator should help, but I would add a PRV and bleeder at the stove. A patch might be to make the PEX connections further from the boiler.

Since you're already seeing heat bubbling of the PEX you need to plan for what to do in a power failure when there will be no powered circulation.

You now have a "mini" boiler which should be subject to the same overheat safety controls as a "real" boiler.

 
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Post by traderfjp » Tue. Oct. 28, 2008 12:32 am

I agree that I would try to salvage what you have and see what a circulator does. You'll have to use one anyway if you discover that you need to re-plumb the whole setup. One thing that really concerns me is that you see bubbling in the Pex. If that gives out you're going to have a mess on your hands and the insurance company will probably not cover the damage. If I was you I would disconnect the Pex and run the coil dry until you can get it all fixed. The plumber needs to come back and make it right. I wish you were local because I would help with some of the fixes. Do u do any plumbing? It really isn't hard at all. I can run you through the steps. I also noticed he used galvanized with black pipe. I don't think it's a big deal but a lot of plumbers would never do that and would have just used black pipe and fittings for everything. I would also get him to install elbows so the pipe lies on the side of the stove. It also looks like the coil needs to sit further into the stove so the elbows are flush with the side of the stove. Maybe you can run the copper into the basement and then use the Pex from there. That way if you have a failure the mess is contained to the basement area. The temps from the stove can get the water to 180 degrees and the Pex starts to fail around 200 so I would not feel comfortable with using it but you have to make that decision. I still don't think you will be able to heat the boiler-mate tank since it's an indirect system. The coil sits in a bath of water. Usually in 160 or more degree water which heats the water running through the coil. I don't think you have enough coil to do what you want. A lot of guys have success with a tank and then running the water from the coil directly into the tank. Give it a try the way you have it but be careful with the Pex pipe. The insulation I have on my pipes has all melted onto the pipes so the temps do get up there. The post before me has some good advice about the PRV at the coil and to think about a power failure because the water will stop circulating and the water in the pipe will turn to steam real fast.


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