Starting my "storage and replumb" project

[warno]

I put a bigger fire in the box tonight, and got it up to about 160 degrees. But my plate HX draws some much heat from the boiler water it was sending 75 degree water back to the boiler. I don't know if that's just because the storage water started out at 65 degrees or what. But I was checking the ports of the plate HX with my temp gun and it said 155 entering boiler side and 75 leaving boiler side. I have a caleffi thermomix valve as return protection, which was working overtime. The storage side was 65 entering and 95 leaving, I'm ok with that.

If my storage is closer to target temp will my boiler return temps be better?

I couldn't seem to get my boiler much over the 160 mark while running the plate HX. I was seeing flue temps of well over 400 degrees. So I have the heat, I just need to get it into the water. I have a turbulator idea that I'm hoping will work. How much better is it to run a turbulator vs not?

I got the top of my storage up to about 110 from about 65, after a 3 hour burn. My combustion fan went into thermal shut down from getting too hot. It was cycling on and off but my damper stayed open so it would at least natural draft when the fan wasn't running. I think I need to put in another vent down low in the boiler shed to draw in cool air from outside. Do you guys think that will be enough to cool the fan down? I already made a heat sink for the fan, I'd hate to have to put a cooling fan on my combustion fan.

Here's my fan now.

 

[maple1]

I don't have a whole lot of experience with plate HXs, but I do have one. That's a big difference in DTs between sides - 80 on the boiler side, and 30 on the load side. Which I'm thinking says there's a flow imbalance between sides. I think they should theoretically be the same on each side. The 30 sounds not bad, the 80 is a lot. So I think there should be more flow through it on the boiler side - but that is compounded by the low startup temps, and the boiler bypass bypassing most of your flow to maintain decent boiler return temps.

I think I would run it like this until you get your storage temps closer to where they are normally going to be when heating, then see how the HX temps level out at. As storage rises, your bypass should bypass less, then your flow should improve through the boiler side of the HX. Assuming a 'typical' DT of 20° through the boiler, and a protected return temp of 140, I would say your boiler is doing OK at present and wouldn't expect to see much more than 160 on it until your storage return gets hotter. I see right at 160 on boiler supply & storage top on my first lap through storage - and if storage is fully cold, that first lap can take a long time since most of the boiler flow is going around the bypass to maintain 140 return.

Not sure what to say about the fan - I don't even have one so even less experience there. Can you tell if heat is creeping/conducting back through the fan piping, from the boiler inlet to the fan? If so, some kind of gasketing for a thermal break might help. But also thinking the heat sink should be on the top side of the fan, otherwise the heat it is shedding will rise right into the fan again. Is the sink very hot?

 

[warno]

Thanks maple, I'll keep running and stuffing wood in the thing until storage gets up higher. I just finished refilling after draining my pretreatment. So maybe tomorrow morning I can start trying to heat again. Interesting thing though I left my garage heating coils running all night to circulate the pretreat and when I went in at 6 last night and came out at 3 this morning I couldn't tell if the needle had moved from the 110 at the top header. And the tank pile was warm all the way down so I am getting heat to the bottom.

I switched fans and went back to "ol' trusty", my fan from last year, I don't think I ever remember it shutting down even at start up. I don't have it hooked into my potential secondary air passage but it seemed to run pretty good last year without it. I don't think the secondary idea was working anyway. The reason I think this is because my chimney was pretty smokey while burning. Until it got really going anyway. I know, I know, I'm not hot enough with this type of boiler. I was burning oak 4x4 lumber which I hope was the reason for the smoke. It's possible the lumber had traces of oil and other crap on it and possibly not dried enough.

 

[warno]

Ol' trusty back in action. Wiring is alittle hack but it's temporary until I figure out if this will work.

Roughly a half hour into the burn. Flue temps...

The heat is there just need to put it in the water better.

EDIT: about 1 hour into burn flue temps have sorta leveled out around 550. Alittle wisp blue/white smoke from the stack.

 

[Fred61]

Haven't followed this install thread because I had been traveling and doing my chores at home. Just did a bulk read and am very impressed. The one thing I noticed that may be a problem in the future is not isolating the air eliminator from the air scoop with a ball valve. Like your circulators, these are prone to failure and need to be changed out in the furure. Having to drain down the system just to change that little devil can be frustrating. Ask me how I know.

 

[warno]

Thank you for the compliment.

The one thing I noticed that may be a problem in the future is not isolating the air eliminator from the air scoop with a ball valve.

It is a caleffi air eliminator and it comes with a check valve for removal. So I can remove it without draining the system. Good catch though. That would have been annoying without it.

 

[warno]

Update about 3 hours into burn. Ol trusty still kickin, just now getting warm. The other fan I couldn't touch after about an hour. Flue temps still up there.

Here's my plate HX readings

Boiler in

Boiler out

Storage in

Storage out

It seems to be pulling the heat down through the tanks well. I did notice the top wasn't heating like it did the other day. I was only reading about 90 on the top temp gauge. Well I noticed my expansion tank drain valve was open still from filling yesterday morning. I closed it and the temp shot up to about 105 in a matter of minutes.

 

[DaveBP]

Adding home-made turbulators to my Tarm Solo reduced the outgoing flue temp very nearly 100F.

And I don't think you can take any conclusions from your system until you have the storage tank temps up to at least 90F (or more) top-to-bottom.

 

[warno]

I left the fire dieing in the box after a 5 hour burn and got the top of the tanks to about 115 and the bottom to about 105 or so. For what it's worth they felt warm to the touch throughout. I would like to get a thermal image but I don't have the equipment for that.

I burnt every splinter of wood I had on hand, about 2 wheel barrel loads. That's why I stopped. I need to load up from the drying pile and light up again. My father and I burn from a common pile on his property. Time to visit the folks.

Also I think I will be adding the extra vent hole in the boiler shed. With sustained 500 degree flue temps the shed got VERY hot. Couldn't hurt, right? Maybe I'll throw a damper on it with a thermostat to open and close it so I'm not getting cold winter winds whipping through.

 

[maple1]

Could you insulate your flue pipe? With rockwool stuff or the like?

 

[warno]

Yes I could insulate it to some extent. This is the amount of bare steel I have hanging out before going into the double wall chimney pipe.

Best pic I have on hand, but you can see the rectangular heat exchange tube coming out into the flue adapter. I could insulate the area. That should help quite a bit. I'll start collecting our rockwool scraps from work and try out it. Thanks for the idea.

 

[warno]

I tossed in another load of wood tonight is burning down now. It took about an hour for it to start burning clear out of the chimney, which I need to work on. But I checked on it about 3 hours later and I had a huge pile of coals (oak and hedge). So I raked them up and tossed in another load of oak. It took about 1/2 hour to clear up to a faint trail of smoke.

I started the fire with about 90 degree water in the tanks when I reloaded it was just over 100 to and bottom. Which leads me to a question:

How long does it take to heat this much water in general?

And when charging storage should it be pulling the heat all the way down the tank or does it load the top then stack down? Mine seems to be balancing out top and bottom when heating the tanks.

 

[jebatty]

How long does it take to heat this much water in general?

You can calculate this quite easily, subject to the variable of the efficiency of your boiler and efficiency in transferring hot water from the boiler to storage or to your system. Seasoned wood (20% MC), has 6050 btu/lb of available heat energy at 400F flue temperature. One btu raises one pound of water 1F, and one gallon of water weighs 8.34 lbs. Assume about 80% efficiency in boiler/system transfer of heat to water in a 1000 gallon storage tank.

1000 gallons of water in storage weighs 8340 lbs. Therefore, it takes 8340/6050/0.82 = about 17 lbs of wood to raise the entire 1000 gallons of water 1F.

To answer your question, the length of time is the time it takes to burn wood of known weight and doing the calculation.

As you have noticed, your boiler shed becomes quite warm. Those are btus not being transferred to the water. Depending on the location of the boiler and storage, total system efficiency can be quite a bit better than 80% if that "lost" heat becomes usable in some way. My boiler and 1000 gallon storage tank are located in my shop, my flue temp roughly ranges between 350-450F during a burn cycle, but all the heat thrown off by the boiler and the flue, as well as piping between the boiler and storage and any heat lost by storage through the insulation also heats the shop. Total system efficiency in heating my shop may approach 90%,

 

[warno]

So I need to burn alot more wood to get it up to temp. lol I wish I could have had my flue temps heating the garage too but the insurance didn't want my fire in the building structure so the shed is about 10 feet from the garage plumbed in under ground.

I was doing sound thinking last night and I think I figured out why I have such a difference in my T across my plate HX. My boiler has about 20 feet of thermopex 1" to run through with a butt weld 90 elbow and a 45 degree sweat elbow, so not alot of head loss there but I'm thinking my diverter valve is adding way too much head to the boiler line. it's port for water to flow through is, at best, 1/2". so I'm thinking that is is slowing the boiler water down tremendously allowing the plate HX to do what it does and take a huge amount of heat from my boiler side. leaving me with really low return temps meaning my return protection valve stays partially closed not allowing maximum flow to my HX. could this be my problem at the boiler side of the HX?

This is my valve

 

[maple1]

Are you using that for boiler return temp protection?

I have no experience with diverter valves - but this is more like what others are using for boiler return temp protection:

http://www.supplyhouse.com/Caleffi-280166A-1-Male-NPT-ThermoMix-Thermostatic-Mixing-Valve-140F

 

[warno]

No I'm using it as a diverter if I need my heat dump to run.

It's right here

 

[maple1]

Ah OK, I thought I was seeing it on the back of your boiler.

CV=7.5, it might be throttling things some. Curious what others would say - over my head a bit with it. But thinking it would flow like a zone valve, and I don't think I would want something flowing like that, on my boiler loop. (Seat of the pants thing only....). The Thermomix I randomly clicked on had CV=10, I think.

 

[warno]

Just alittle update on things. I have been trying to heat the tanks I have gotten to about 130 so far. I think I'm losing to much heat through radiant off the tank surface so I'm thinking about doing the spray foam kit from ebay to get some insulation on them. anybody had any luck with those kits?

Also I noticed my pressure at the top gauge is reading next to nothing and the bottom is reading almost 20. should I be seeing this much pressure difference?

 

[huffdawg]

Just alittle update on things. I have been trying to heat the tanks I have gotten to about 130 so far. I think I'm losing to much heat through radiant off the tank surface so I'm thinking about doing the spray foam kit from ebay to get some insulation on them. anybody had any luck with those kits?

Also I noticed my pressure at the top gauge is reading next to nothing and the bottom is reading almost 20. should I be seeing this much pressure difference?

U would think u could get it above 130?

 

[huffdawg]

I didn't use the kits.. I had a spray foam contractor come in... he had a groan of a time spraying anything that he couldn't get the wand a couple ft away..

 

[huffdawg]

I didn't use the kits.. I had a spray foam contractor come in... he had a groan of a time spraying anything that he couldn't get the wand a couple ft away from.QUOTE]

 

[warno]

I think it will go above 130 I just haven't had time to sit out there and feed it to keep the fire going.

I'm going to call a spray foamer this week to get a quote.

 

[warno]

I have the spray foamer coming to do the job tomorrow on my tanks. he asked how hot they could get, I told him possibly 180. I was going for maximum high number. he said that he would call his chemical dealer to ask if the foam will be ok at that temp. I haven't heard back from him about the dealer recommendation so I'm guessing we are good, but he has me wondering if it will be a problem. so I ask those of you who have had your tanks foamed with closed cell, does the foam hold up to high temps very well?

 

[leon]

Save your money and buy 4 rolls of the 6 inch by 18 inch batts of roll insulation without the moisture barrier or aluminum facing and just throw it over the top and pull it down and tape the batt ends and sides together and do the same thing on the ends of the tanks. The duct tape wont care where its used and the fiberglass insulation will not be affected by the heat.

People insulate tanks with household insulation all the time and use chicken wire to hold it in place.

 

[Beagle Dad]

The 180°F will not hurt the foam. I used foam to maximize the R value and minimize the overall final tank diameter. The tanks were sprayed with an average of 2.5" of foam for an R value of just over 15. The tanks in the picture were sprayed in the basement, cladded then piped. When at temperature the tanks lose about 0.75% per hour initially.