Can you "hear" your water flowing into storage?..

[Singed Eyebrows]

Randy, the inlet and outlet are both 1.25" pipe and they are right in the center of the headers. I definitely agree that it shouldn't be kettling, but if there is a flow problem in one or more of the tubes, why does it get worse with a higher flow rate? I can't think of any reason it would do that with more flow.

As far as some kind of deposit in the HX, I really don't know. My water is not really hard and I've never had any other problems with the propane boiler that has been in the system for 11 years.

Pat

Pat, The pipe size doesn't appear to be the problem. Somehow the exchanger is not flowing properly. The one poster said excessive pump flow might be screwing things up & this is possible. You had no problems with no storage & Fred Seton does not advise storage. Maybe he knows something we don't. I don't know if the additional feet of head pumping into your tank is causing problems etc. I would start with the IR gun on the exchanger. If you have some hot tubes on the oposite side of the inlet you will probably need 2 inlets as mentioned, each side of header. What would be really nice would be to get a thermal imaging Flir gun on the exchanger. The IR should do though. Randy

 

[Singed Eyebrows]

I don't know how close you are to Upnorthenergy in Michigan, (broken link removed) Brian is a great guy, engineer also, with thermal imaging equipment, if this is not readily fixable, Randy

 

[Singed Eyebrows]

OK, One more thought before I call it a night. When this ran without storage water enterered the bottom runner & flowed up through all the tubing into the top runner & out. Now you added some restriction with the tank & this is at the outlet of the top runner. It's probable that water is now going into some of the bottom runner tubes up to the top runner & back down some other tubes & circulating. If it does this it will kettle & bang. The solution if this is the problem? 2 inlets should do it. Better, is to take a sawzall & make a series exchanger out of this. Just cut the runner braze in a plate(about 4 tubes over for flow) & so on through the exchanger. Then you will get positive up & down flow through the whole thing, Randy

 

[2.beans]

did you build your own hx?

 

[Pat53]

Randy, when I was running last year without storage, I had a Taco 0011 and it worked great. However, I was running about 80 feet, one way, with 1" kitec and then into 1" copper and then into my existing propane boiler which had 3/4" ports, so I would think the head pressure was much higher than what I have now with storage. I have no idea what my flow rate was, but the system ran flawlessly. Needless to say you get a lot of idling without storage, and by the end of the season, the water tubes behind the refractory were gunked up pretty bad. I was able to keep the tubes above the firebox relatively clean with weekly scraping.

So I decided to go with storage this year and now I have this problem. I wanted to go with a bigger pump to be able to keep up with the hotter burns and not have the boiler go into idle mode as much. That is working OK I guess. When the tank temp is down to 150F, I can run for 3-4 hours to get up to 185F or so, but I am trying to kep the stack temps from getting too high to limit the kettling, so I have to make more trips out to the boiler. I don't want to just load it up with wood and walk away. I would be getting 500F stack temps and a LOT of banging I'm sure.

If I understand what you are saying, is that the water is going thru the center portion of water tubes and circulating back down the outside tubes and thus overheating in those tubes? I don't see how that is possible. The water is being forced into the lower header and the water has no where to go but up the tubes, into the upper header, and out the outlet. I can see how the water in the outside tubes would be little hotter because it has a longer route to take and therefore longer time exposed to the heat, but there are a lot of people using these type boilers and they don't seem to have this problem.

I talked with Fred Seton a few days ago and I asked him if it is possible to use too big a pump and have this problem and he said no. a bigger pump would simply move the heat off the HX faster, which would make sense. I do agree that adding multiple inlet ports into the lower header would make for better more even flow thru the HX, but evidently is needed or everyone using these type boilers would have the same problem.

For now, I'll just have to use it as is until I can figure out what the problem is.

thx, Pat

 

[Pat53]

did you build your own hx?

Yes, a freind of mine and I built the entire boiler. It was built EXACTLY as the plans decribed. We did not skimp or skip on anything. It actually works great, its just a bit noisy !

 

[Piker]

With the thermal storage tanks, you are now quite likely running cooler return temps, yes? Could this be an issue? Does the kettling stop once the return temps start to rise? Perhaps some return water mixing might help? Dunno... just thinking out loud here... might be worth an experiment.

cheers

 

[Pat53]

With the thermal storage tanks, you are now quite likely running cooler return temps, yes? Could this be an issue? Does the kettling stop once the return temps start to rise? Perhaps some return water mixing might help? Dunno... just thinking out loud here... might be worth an experiment.

cheers

No. Even with 170F-175F return water it does the same thing, doesn't seem to make any difference.

Pat

 

[Pat53]

Randy, the inlet and outlet are both 1.25" pipe and they are right in the center of the headers. I definitely agree that it shouldn't be kettling, but if there is a flow problem in one or more of the tubes, why does it get worse with a higher flow rate? I can't think of any reason it would do that with more flow.

As far as some kind of deposit in the HX, I really don't know. My water is not really hard and I've never had any other problems with the propane boiler that has been in the system for 11 years.

Pat

Pat, The pipe size doesn't appear to be the problem. Somehow the exchanger is not flowing properly. The one poster said excessive pump flow might be screwing things up & this is possible. You had no problems with no storage & Fred Seton does not advise storage. Maybe he knows something we don't. I don't know if the additional feet of head pumping into your tank is causing problems etc. I would start with the IR gun on the exchanger. If you have some hot tubes on the oposite side of the inlet you will probably need 2 inlets as mentioned, each side of header. What would be really nice would be to get a thermal imaging Flir gun on the exchanger. The IR should do though. Randy

I tried the IR gun on the tubes, but I can't seem to get consistent readings on them. If I end up having to take the HX out next spring to examine it, I may try to modify the inlet to allow the water to spread out more evenly and quickly, altho I still don't think its neccessary. There is no doubt that the water going to the outside tubes will get hotter than the tubes near the middle of the HX, simply because it spends more time in the HX before exiting. I'm still wondering if I should try adding some kind of boiler additive/conditioner and see what that does?

Pat

 

[Singed Eyebrows]

I think the Seton design is marginal at best. A water tube boiler is normally for high pressure steam applications. Thats not to say they don't work for most people, I'm saying your boiler should tolerate pumping into storage though. The fact that increased pump flow doesn't help the problem sure seems to indicate circulation problems in the exchanger. I believe you when you said you followed specs in building this. You might want to consider modifying the exchanger as I suggested, after the inlet count over 4 tubes & block off with a plate, the water will travel up to the top header, count over 8 tubes & block off, the water will travel down to the lower header etc etc. I do not believe an exchanger like this will kettle & increased pump flow will move water through the entire exchanger in a positive manner. No matter what the cause there is circulation problems in the exchanger you have now IMHO, Randy

 

[Pat53]

I think the Seton design is marginal at best. A water tube boiler is normally for high pressure steam applications. Thats not to say they don't work for most people, I'm saying your boiler should tolerate pumping into storage though. The fact that increased pump flow doesn't help the problem sure seems to indicate circulation problems in the exchanger. I believe you when you said you followed specs in building this. You might want to consider modifying the exchanger as I suggested, after the inlet count over 4 tubes & block off with a plate, the water will travel up to the top header, count over 8 tubes & block off, the water will travel down to the lower header etc etc. I do not believe an exchanger like this will kettle & increased pump flow will move water through the entire exchanger in a positive manner. No matter what the cause there is circulation problems in the exchanger you have now IMHO, Randy

Well, the one thing I can assure you of is that the boiler was built EXACTLY as specified. The guy who did the welding for me is as good as they come. I truly believe he could weld a nickel to a cats a$$ ! LOL

I keep thinking that because I left some water sitting in the HX over the summer that something might have corroded a bit and plugged up one or more of the tubes. The thing that still baffles me tho is why the kettling increases with increasing flow. There is no doubt that the pump is pushing the water thru the HX faster on high speed, as indicated on the outlet temp gauge, so yes, something doesn't make sense within that HX. There are several guys I believe who are using Seton type boilers with storage, and as far as I know they don't have problems. I wouldn't describe the ketling as "violent" , and I don't think it will damage the HX, but it sure as hell is frustrating !

Pat

 

[Singed Eyebrows]

I think the Seton design is marginal at best. A water tube boiler is normally for high pressure steam applications. Thats not to say they don't work for most people, I'm saying your boiler should tolerate pumping into storage though. The fact that increased pump flow doesn't help the problem sure seems to indicate circulation problems in the exchanger. I believe you when you said you followed specs in building this. You might want to consider modifying the exchanger as I suggested, after the inlet count over 4 tubes & block off with a plate, the water will travel up to the top header, count over 8 tubes & block off, the water will travel down to the lower header etc etc. I do not believe an exchanger like this will kettle & increased pump flow will move water through the entire exchanger in a positive manner. No matter what the cause there is circulation problems in the exchanger you have now IMHO, Randy

Well, the one thing I can assure you of is that the boiler was built EXACTLY as specified. The guy who did the welding for me is as good as they come. I truly believe he could weld a nickel to a cats a$$ ! LOL

I keep thinking that because I left some water sitting in the HX over the summer that something might have corroded a bit and plugged up one or more of the tubes. The thing that still baffles me tho is why the kettling increases with increasing flow. There is no doubt that the pump is pushing the water thru the HX faster on high speed, as indicated on the outlet temp gauge, so yes, something doesn't make sense within that HX. There are several guys I believe who are using Seton type boilers with storage, and as far as I know they don't have problems. I wouldn't describe the ketling as "violent" , and I don't think it will damage the HX, but it sure as hell is frustrating !

Pat

I believe the pump is pushing the water through"part" of the exchanger faster on high speed. If the entire exchanger were getting good flow from a strong pump there would be no kettling, provided a tube is not plugged & I don't believe this is happening. This is not like a water tube boiler with a gas or oil gun on it(somewhat moot point as most are steam), the wood fire is very low grade & any decent flow at all through all the tubes & there wouldn't be a problem with banging or kettling. Randy

 

[ewdudley]

[T]he inlet and outlet are both 1.25" pipe and they are right in the center of the headers. I definitely agree that it shouldn't be kettling, but if there is a flow problem in one or more of the tubes, why does it get worse with a higher flow rate? I can't think of any reason it would do that with more flow.

I think you said you've got a 25-30 degF temperature rise through the boiler. At a nominal 130,000 btu per hour that works out to 10.4 to 8.66 gpm. According to the pump curve, to reduce the flow of a 26-99 to 8 to 10 gpm you need about 27 feet of head, or over 11 psi. Yikes.

That's a lot of pressure drop for a pump that's just pumping through the boiler into storage, so there must be a fair amount of restriction somewhere, most likely in the heat exchanger as you suspect. So the harder you pump the lower the pressure leaving the heat exchanger and the greater the opportunity to flash leaving the heat exchanger. This would be true either pumping into the boiler or pulling out of the boiler.

--ewd

 

[Pat53]

[T]he inlet and outlet are both 1.25" pipe and they are right in the center of the headers. I definitely agree that it shouldn't be kettling, but if there is a flow problem in one or more of the tubes, why does it get worse with a higher flow rate? I can't think of any reason it would do that with more flow.

I think you said you've got a 25-30 degF temperature rise through the boiler. At a nominal 130,000 btu per hour that works out to 10.4 to 8.66 gpm. According to the pump curve, to reduce the flow of a 26-99 to 8 to 10 gpm you need about 27 feet of head, or over 11 psi. Yikes.

That's a lot of pressure drop for a pump that's just pumping through the boiler into storage, so there must be a fair amount of restriction somewhere, most likely in the heat exchanger as you suspect. So the harder you pump the lower the pressure leaving the heat exchanger and the greater the opportunity to flash leaving the heat exchanger. This would be true either pumping into the boiler or pulling out of the boiler.

--ewd

Eliot, other than the HX, I can't think of anywhere that a restiction could be. I am running 1.25" black pipe to and from storage. When I added storage I wanted a system with as little head pressure as possible to be able to move the heat as quickly and efficiently as possible into the storage tank. My run from the HX to the tank is about 40 feet and has 1 - 90 degree elbow and 5 - 45's. The boiler and storage tank are at virtually the same height. The return line has 2 - 45's and thats it, almost a straight shot. I know there is no problem with the return, the pump runs smooth and quiet, no cavitation noise ever. The pump is on the return and pushes the water thru the HX. I see now what you mean about the pressure drop, that would make sense if indeed the HX is the problem.

Edit: I forgot to add that there are 4 ball valves in the piping also, and they are all full port valves.

Assuming there is some type of build-up in the HX causing the restriction, does anyone have a suggestion for an additive that could perhaps unclog the tube(s)? Might as well give it a try an see what happens.

thx,

Pat

 

[RobC]

You could try Wood Boiler Solutions for treatments. They do water testing etc.
If you treat for rust, can you isolate the Boiler from system and only treat that so you don't flush crud downstream ? If you can get boiler clean you could then treat whole system.

 

[2.beans]

when you increase pump speed your supply temperature to storage rises?

 

[Pat53]

when you increase pump speed your supply temperature to storage rises?

No, it will go down a bit.

 

[mole]

[/quote]

Eliot, other than the HX, I can't think of anywhere that a restiction could be. I am running 1.25" black pipe to and from storage. When I added storage I wanted a system with as little head pressure as possible to be able to move the heat as quickly and efficiently as possible into the storage tank. My run from the HX to the tank is about 40 feet and has 1 - 90 degree elbow and 5 - 45's. The boiler and storage tank are at virtually the same height. The return line has 2 - 45's and thats it, almost a straight shot. I know there is no problem with the return, the pump runs smooth and quiet, no cavitation noise ever. The pump is on the return and pushes the water thru the HX. I see now what you mean about the pressure drop, that would make sense if indeed the HX is the problem.

Edit: I forgot to add that there are 4 ball valves in the piping also, and they are all full port valves.

Assuming there is some type of build-up in the HX causing the restriction, does anyone have a suggestion for an additive that could perhaps unclog the tube(s)? Might as well give it a try an see what happens.

thx,

Pat[/quote]


Pat,
This problem is strange and the strangest part, as you say is that the flashing gets worse when you increase the pump speed. Just doesn't make sense! I feel bad for you after all that work. A couple more thoughts:

You mentioned that your system runs at a low pressure of about 6psi and a high of about 18psi when up to temp. How does this compare with the old configutation? How does the pressure gauge on the supply change when you change the pump speed? Maybe the old configuration had a lot more backpressure due to the long 1" lines?

In theory, raising the system pressure should raise the boiling point of the water and decrease the tendency to flash or bump. What happens if you bump up the pressure setting on your autofill? Can your expansion tank handle that, at least on an experimental basis?

How does the house heating system tie into the boiler/storage storage loop? Is it configured in a way that a pump for the house heating system could bew dropping the pressure in the boiler tubes?

Going back to the low flow concept - What was the temperature differential through the boiler on the old system? It sounds like you should have at least 50% more water flow with the new storage system. If this were true, you'd expect the dT to drop by 1/3 roughly with the new configuration?

Another thought is that maybe one of those ball valves isn't working properly. I know they are fairly reliable, but I saw a 3" full port ball valve fail once where the handle turned and appeared to work, but the valve body didn't move! I'll admit it's a long shot.

JR

 

[Pat53]

Hi Mole, I've tried upping the system pressure to 25 PSI at the boiler and it made no difference. Currently when the storage tank is cold (150F or so), the system pressure will fall back to about 8 PSI at the boiler and about 14-15 downstairs in the propane boiler. The boiler pump works fine and never cavitates or makes any noise even at the low pressure. Before I had storage I ran with about 20-22 PSI, and with the low system water volume and smaller temp ranges, the pressure varied only a little.

I see no difference in what the water temp is when the boiler is kettling. the return water can be 145F or 175F and if I get a hot fire going it will make the noise. same thing with the system pressure. makes no difference if pressure at the boiler is 10 PSI or 22 PSI, a hot fire will make it kettle. I don't seem to notice any change in pressure on the boiler gauge when I increase or decrease the pump speed, but the flow rate definitely changes according to the outlet temperature.

I have a 44 gallon expansion tank on the system and as far as I know it is working fine. It will fill up a bit on high pressure and vice-versa.

Currently I'm just drawing hot water off the storage tank and pumping it into my existing LP boiler and back to the tank. The circulator that supplies hot water to the boiler only kicks on when one of the 3 house zone circulators kicks on. I don't see any change in pressure when those zones come on, and everything in the house is working great. lots of heat and running smooth and silent.

According to my calcualtions, my head pressure for my primary loop from boiler to storage should be less than 7 feet at about 15 GPM, plus whatever the HX might be. the fact that I'm getting the kettling and such a high Delta T across the HX would indicate that my flow rate is too low even tho I'm using a pretty big pump, and so the theory that the HX is in some way plugged or impaired. My old system last year only had a 20 degree aquastat that would shut the draft on the boiler down at 185F and come back on at 165F, but the entire system only had about 40 gallons of water. I agree that the the Delta T should be much lower with the system I have now, but its not.

I checked all the valves before installing them and they were working fine. I really doubt they are faulty.

thx, Pat

 

[barnartist]

Moderator may want to make this its own post, hope this is not a hijack...

I recently had to run 220v strait to my laddomat pump because the transformer I was using died. Before this change I could only hear my water running to my storage if all else was quiet. Now I can really hear the water moving, it must be a huge amount. My guess is the hz change from 50 to 60 has made it run faster. Im not sure if this is good or bad yet, but my tanks seem to be charging ok. I am wondering if the laddomat did not run correctly before with the transformer, or if the new power connection is correct. Since this unit has 3 speeds, I may experiment with turning it down.

Having said all of that, I am experienced at knowing when I have air in the system or not, this is definately all water movement. Not sure if this helps with the post, but maybe allot of elbows and such on a short run with a powerful pump may amplify the sound. I am reminded of the sound a running garden hose makes when you attempt to pinch the hose in an effort to stop the water flow. Anyway thats what mine sounds like right now amplified.

If anyone has an ideal way for me to get the correct flow rate please chime in.

 

[Singed Eyebrows]

Moderator may want to make this its own post, hope this is not a hijack...

I recently had to run 220v strait to my laddomat pump because the transformer I was using died. Before this change I could only hear my water running to my storage if all else was quiet. Now I can really hear the water moving, it must be a huge amount. My guess is the hz change from 50 to 60 has made it run faster. Im not sure if this is good or bad yet, but my tanks seem to be charging ok. I am wondering if the laddomat did not run correctly before with the transformer, or if the new power connection is correct. Since this unit has 3 speeds, I may experiment with turning it down.

Having said all of that, I am experienced at knowing when I have air in the system or not, this is definately all water movement. Not sure if this helps with the post, but maybe allot of elbows and such on a short run with a powerful pump may amplify the sound. I am reminded of the sound a running garden hose makes when you attempt to pinch the hose in an effort to stop the water flow. Anyway thats what mine sounds like right now amplified.

If anyone has an ideal way for me to get the correct flow rate please chime in.

As mentioned you were running 60hz either way, with or without the transformer. You can run this off a "true sine" Euro inverter(Ebay), they are 12V to 220v 50hz. This will slow the pump some & you can dial it in further if needed with the 3 speed switch. I would avoid the modified sine inverter as these could cause problems. Randy