Mixing valve is FPE Model 2010.
Not sure why the piping would be too small, as long as I'm keeping the boiler loaded down and not idling there shouldn't be gpm issue? The boys at Econoburn thought 1.25 was plenty. the Boiler loop is 2".
Heating Storage Tanks
- Thread starter markburtenshaw
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Mixing valve is FPE Model 2010.
Not sure why the piping would be too small, as long as I'm keeping the boiler loaded down and not idling there shouldn't be gpm issue? The boys at Econoburn thought 1.25 was plenty. the Boiler loop is 2".
Well, your boiler at full output is 300,000 (rated). So, 300000 = 500 * GPM * Delta T (which you wanted to keep at 30). So, 300000/(500*30) = 20 GPM.
On the diagram you posted previously, what ports are where? I didnt see them labeled. Also, how are you controlling all of this stuff?
On the diagram you posted previously, what ports are where? I didnt see them labeled. Also, how are you controlling all of this stuff?
Getting somewhat off topic, but 1.25" is good for 15 gpm at 3.9 ft per second, even 20 gpm at 5.22 ft per second wouldn't be much of a stretch. As always it all comes down to deltaT and 30 degF deltaT shouldn't be unrealistic at all, so 300,000 btu per hour or 80 kW should be easy enough with a 20 gpm pump.
However, not with the system shown in the schematic if I'm reading it right. Also, how does heat come back out of storage?
I put a bypass around the mixing valve incase it ever fails, there is a manual ball valve to open or close it. If it fails I have the pump programmed to a PID loop (direct injection) where I monitor the return temperature and the supply temperature of the boiler as to not allow too much colder water in.
Looking at the pdf I posted I should likely update it a little, it wasn't installed exactly as drawn. I'm controlling everything with the on board controller on the Econoburn as well as a modicon plc so I can monitor everything on my phone!!
The tanks have separate in/outs for heating from the boiler and separate in/outs for supplying heat to the house. I push hot water in the top of the tank and pull cold water from the bottom of the tanks. But I have the return water from the house also pushing into the bottom of the tank.
maple1
Minister of Fire
If the boiler is not idling in all this, then where is the heat going? There should be a lot of it going somewhere.
How dry is your wood? Are your stack temps good?
How dry is your wood? Are your stack temps good?
I'm not familiar with all types of installations but after going back to the schematic two things stand out. First is that your valve is on the supply side and second I don't understand the line with the pumps in it that appears to be short circuiting your return from the mixing valve. I think you will get more accurate temperatures to the return with the valve on the return side. Perhaps someone with more knowledge could explain this design to me.
Wood is about 18%, I have never checked the stack temps, what should they read? I have an IR gun.
In StorageTanks-Model.pdf, where are ports A, B, and C for the Model 2010 Three-Way Thermostatic Valve?
Also, if the storage tanks ever did get hot, how would hot water from the top of the tanks find its way into the primary loop upstream of the loads?
the line that comes from the bottom of the tank where the water will be the coolest is connected to Port C of the mixing valve. Port A is hooked into the return of the boiler and Port B the supply of the boiler.
Hot water from the top of the tanks are on separate supply and return lines to/from the house, that way I can heat the tanks while heating the house at the same time.
maple1
Minister of Fire
It might be me (likely is), but I can't wrap my head around the schematics, or I guess relate what I am seeing in them to your explanations of how the flows are going.
I would think that if you aren't sending heat to your storage, then the boiler would be idling - a lot. But you say it isn't idling - so there must be heat going to storage? That is compounded by the size of the boiler - that thing is big. It has to be sending heat somewhere. A lot of it.
What are the temps at your boiler out & boiler in fittings when burning? Does boiler in (return) stay at a constant temp? Usually in the 140-150 range? Maybe it's working right and you just haven't burned enough? How long have your burns been? Doesn't sound like you've had many of them?
I would think that if you aren't sending heat to your storage, then the boiler would be idling - a lot. But you say it isn't idling - so there must be heat going to storage? That is compounded by the size of the boiler - that thing is big. It has to be sending heat somewhere. A lot of it.
What are the temps at your boiler out & boiler in fittings when burning? Does boiler in (return) stay at a constant temp? Usually in the 140-150 range? Maybe it's working right and you just haven't burned enough? How long have your burns been? Doesn't sound like you've had many of them?
What you describe does not jibe with the schematic you published. On the schematic the mixing valve is situated between the boiler loop and the primary loop. Also on the schematic there is one line to the top of storage and another line from the bottom of storage, there is no separate supply and return. Are you sure the plumbers installed the piping according to your schematic?
Yes, I'm going to redo the schematics I jumped the gun posting them because I haven't updated them to what I have actually installed. This thread is a little off topic from the intended, I'm am putting heat to the storage my supply temp ranges from 175 to 185. and you have asked the question that I have been trying to explain from the start. I've been trying to figure out what that return temp is supposed to be, currently I'm using direct injection to heat the tanks. Meaning I close off the mixing valve and use my bypass to bring cold water from the tanks directly into the boiler return. Problem is that water from the bottom of the tank is 100 deg, so I can't run the pump from the boiler to the tanks for too long, I let it see a return temp of 135 then I stop the pump. this usually takes about 10 seconds, then I let the return charge back up to 170 and repeat the process. So what your saying is if my mixing valve is working properly I should be able to have constant 140 to 150 water in the return of the boiler and it should be able to keep up a supply temp of 180ish? Now we are getting somewhere!!
That's how it's supposed to work, return temperature should remain no less than setpoint, 140 degF, 150 degF, or whatever according to the particular thermostat you have inside the valve.
But supply temperature is then determined by how much flow the boiler loop pump generates, and the rate that the boiler generates heat.
For instance if return temperature is 140 degF, and boiler loop pump is moving 17 gpm, and boiler is putting out 220,000 btu per hour, then temperature rise through the boiler would be about 26 degF and supply temperature would be 166 degF.
On most boilers you can adjust the 'launch temperature' so that the boiler loop pump circuit makes on boiler supply temperature rise (e.g., 185 degF) and then breaks on supply temperature fall (e.g., 180 degF). (This assumes that supply temperature sensor can see the temperature at the top of the boiler with or without the boiler loop pump running, which is normally the case.)
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Armaton
Member
If the actual piping follows the schematic, it does appear that the "Thermostatic" mixing valve is incorrectly placed. It is for boiler protection and should be taking the output of the boiler and mixing some colder water from the return (from house or tanks) and insuring the return water is not below 140 degrees to the boiler. It appears that the mixing valve is adding return water to the supply and insuring 150 degree water to storage and loads.
maple1
Minister of Fire
So what your saying is if my mixing valve is working properly I should be able to have constant 140 to 150 water in the return of the boiler and it should be able to keep up a supply temp of 180ish? Now we are getting somewhere!!
Yes, correct. The main rule is no less than 140, that is to avoid increased creosote condensation in the box. You mentioned boiler shock early on - I'm not sure on that aspect to your boiler, you'd maybe want to check with your manufacturer about that. But seems to me I'm thinking from all I've gleaned here that if you keep return above 140, that also makes boiler shock a non-issue. I know when my old one was installed 18 years ago, the installers told me the bypass loop it had on it was to prevent boiler shock - but boiler shock is not something that is talked about on here much at all or doesn't seem to be worried about.
If you've already got a thermostatic mixer, this should be way easy if it's plumbed in right. There will be no starting & stopping of pumps or opening & closing of valves like it sounds like you're doing - the boiler pump will start when the boiler is up to temp, and stop when it drops when the fire goes out. The thermostatic mixer does the rest.
Yes, correct. The main rule is no less than 140, that is to avoid increased creosote condensation in the box. You mentioned boiler shock early on - I'm not sure on that aspect to your boiler, you'd maybe want to check with your manufacturer about that. But seems to me I'm thinking from all I've gleaned here that if you keep return above 140, that also makes boiler shock a non-issue. I know when my old one was installed 18 years ago, the installers told me the bypass loop it had on it was to prevent boiler shock - but boiler shock is not something that is talked about on here much at all or doesn't seem to be worried about.
If you've already got a thermostatic mixer, this should be way easy if it's plumbed in right. There will be no starting & stopping of pumps or opening & closing of valves like it sounds like you're doing - the boiler pump will start when the boiler is up to temp, and stop when it drops when the fire goes out. The thermostatic mixer does the rest.
Armaton
Member
Went to the site for your valve, it doesn't look like it's made for the application you are trying to use it for. I could be wrong, but it appears that in mixing and diverting, it is only concerned about temp of water to the loads, not to the boiler.
Edit: Site picture was throwing me off, it could work in the mixing mode, if Port A is boiler return, Port B is Boiler supply, and Port C is load return. But you would have to swap the boiler loop Tee and mixing valve in the plumbing schematic.
Edit: Site picture was throwing me off, it could work in the mixing mode, if Port A is boiler return, Port B is Boiler supply, and Port C is load return. But you would have to swap the boiler loop Tee and mixing valve in the plumbing schematic.
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A quick update. Thanks for all the input from everyone! I had a great break through day on the weekend. After speaking with everyone here and tech support from the manufacturer of the mixing valve I was told that in my application most people request a 'weep hole' in the thermostat to allow cold water through the mixing valve when the tanks are very cold. He said usually about a 1/16" would do the trick. He said to take the valve apart and drill a hole....I mentioned that I had a bypass looped around the mixing valve direct to the boiler return (sourced from the bottom of the storage tank), so I would just try cracking it a tiny bit until my return temp was a constant delta of 25 to 30. This worked really well, the storage tank to boiler pump stayed on constantly and the boiler had a constant load running at about 185 supply temp. I was able to take the tanks from 70 degF to 140 degF in about 8 to 10 hrs of solid burning and didn't have to mess around with anything. I also started looking at my stack temps, when things were really going I was seeing about 330 coming out of the flue (on the single walled chimney attached), is this normal? Wood feeding was maybe a little high in moisture measuring between 23 to 28%.
maple1
Minister of Fire
Good to read of breakthroughs.
On stack temps, you'll likely have to wait for feedback from an EB owner. But I see about 200c on mine at full burn - measured with an internal probe thermometer. If you're tyring to guage/compare your stack temps to others, you should also compare how they're measured. Example: I have a magnetic surface temp guage right beside my probe guage, it reads 100c less than the probe temp at full burn.
On stack temps, you'll likely have to wait for feedback from an EB owner. But I see about 200c on mine at full burn - measured with an internal probe thermometer. If you're tyring to guage/compare your stack temps to others, you should also compare how they're measured. Example: I have a magnetic surface temp guage right beside my probe guage, it reads 100c less than the probe temp at full burn.
Do you feel secure about being able to keep the return water temperature above the minimum of 140
using the manual method?
using the manual method?
Do you feel secure about being able to keep the return water temperature above the minimum of 140
Yes, after watching it all day Saturday its not going to be an issue. I have checks/logic in place (RTD hooked into my PLC) to stop the storage tank pump if the return to the boiler dips below 145 or whatever I want to set it to. As well I monitor the boiler supply temp to make sure my delta stays within an efficient range.
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