Cleaning heat exchanger? Something else?

[mtfallsmikey]

TMH:

Take a look at Webstone/Apollo 3-way valves, made for flushing tankless water heaters, that would be a good solution. Also, as I have recommended before many times, get the books "Pumping Away" and "Primary-Secondary Piping Made Easy" by Dan Holohan, at Heating Help - Heating Systems. All shall be revealed for ye...

Rep for your efforts.

 

[themaddhatter]

TMH:

Take a look at Webstone/Apollo 3-way valves, made for flushing tankless water heaters, that would be a good solution. Also, as I have recommended before many times, get the books "Pumping Away" and "Primary-Secondary Piping Made Easy" by Dan Holohan, at Heating Help - Heating Systems. All shall be revealed for ye...

Rep for your efforts.

Thanks Mikey. I have done theoretical stuff involving flow and pumping stuff in college (unit ops stuff), but the practical aspects are always of more use. And that was 15 years ago.

I will take a look at those valves. I would have liked to have done something a little "cleaner" rather than having a dozen ball valves staring at you, but when you are in a bind and have the nearest big box 30 minutes away, you kinda make due with what you can get.

 

[tanker]

Update:

Long day yesterday, redid several things (based on supplied photos in PM from Iska (thanks again)

- First, flow was incorrect through exchanger. I had assumed (and we know where that gets us) that the PO plumed it right. Yeah.... So redid how the flow goes through (in through top, out through bottom)
- Second, I disconnected a Modine he plumbed in series to put heat in basement. Put manifolds on feed and return to control individual units (still have to connect Modine to manifold, but just wanted to get things flowing)
- Installed y strainer (to help clean stuff out)
- Added spigots with ball valves on manifolds to allow forward and backward flushing
- Removed couple remaining gate valves from PO and put in bleeder ball vales (system is now gate free - God I hate gate valves)

Got everything plumbed, and dealt with a couple leaks (an extra turn here and there on pipes). Forward flushed then backward flushed all in-house with house water, and saw a good bit of sediment and air pulsing blow out. Did 2x until I had 5 gallons worth of clean and laminar flow. Opened feed and return at OWB, and bled air on feed side to pump. While keeping the return closed in the house, opened spigot on return side, saw laminar flow. Plugged in circ pump, and saw increase in flowrate (pump is moving water just fine). Opened return in house, and heard a little bit of water knock for about 2 seconds, then silence... I think I have got it licked now Came up from the basement, and it was 12:30. No wonder I was tired.

As soon as sun came up, put a new gasket on door (needed it), started a fire, and we will see how it heats things up today.

Observations:

- Was a couple of unions on heat exchanger to allow for pulling unit. PO had done a piss-poor job doing the solder job, and slobbered solder on the face of the union (part where threaded nut presses against), creating a wobbly union. His remedy for this was to tighten the unions using the power of Odin or something, because I had to put a little heat on the nuts to get them loose. And he recta-sealed the threads :bang: Always been told to NEVER put sealant on union threads. If the seat is done right, should only need to be threaded on and tightened. So, I heated up the union and cleaned off his ancient cruddy solder off the face and wiped it down. Cleaned as much recta as I could, and seats well now without leaks.

- Definite improvement in purging/flushing/backflush capability by doing spigots on both sides with manifolds.

- OWB held a BUNCH of heat during the downtime. Valves closed in the morning, with stove at 140. No wood had been put in for 24 hours, and even then was only like 4 pieces ~ 6" in diameter. Left the power on to the damper to burn anything left in there. At 11 pm when I opened the valves, and the stove was STILL at 140! I was totally shocked with that. Was a mild and wind-free day (high was ~ 40 F). Good example of insulation, thermal mass and residual burn I guess.

- I am going to have to do a mid-season door replacement This door is totally FUBAR. The PO actually built the OWB, and for the most part, he did a decent enough job. I did have to fix a floor leak in it 3 years ago, but that on a system that he built 15 years before I moved in, so that is about 20 years old. The weak spot was by far his door design. The door has a welded piano hinge along one side that is welded to the door and the throat into the firebox. The throat sticks out ~ 2" proud of corrugated steel shell of the OWB. he designed the door to recess around the outside of the throat. Well, the piano hinge started binding this fall, and even though I PB-blasted the hell out of it and hosed spray oil into all the points I could get to, the binding continued, until his tack welds (yes, tack welds) along several sections of the door cracked. Now, the bottom third of the piano hinge is connected, but the bound section just folds over, and this bent folded section is right in the gasket seat area. This forces the door to sit crooked, and keeps the door for seating properly. So much so that I often need to use the back side of a splitting maul at the top corner to get the door to seat and latch. I have a pretty good idea of what I will need to do to fabricate a new door and hinge system. It is going to be interesting on the logistics of doing the swap during the heating season. I will be exploring what others have done for door and hinge designs and adapt it for this scenario (may have to start a different thread on that). Will be designing the door to be able to attach to the throat without welding (dragging a 230 line out to the OWB will be difficult at best, and don't have a generator). If the design goes well, I would only have to cut off and grind off the piano hinge, drill some holes for hinges, backing plates, and latch, and reconnect the solenoid for the damper.

Anyways, enough rambling on. Thanks to everyone for the comments, answers, and suggestions. It was greatly appreciated and helpful!

Will post later tonight after stove has been burning for a while on status.

Now to start that door design.....

I may be goofy(hell, I know that I'am) but on your water to air exchanger,you want inlet on the bottom,outlet on top to get proper flow. Scott

 

[mtfallsmikey]

Thanks Mikey. I have done theoretical stuff involving flow and pumping stuff in college (unit ops stuff), but the practical aspects are always of more use. And that was 15 years ago.

I will take a look at those valves. I would have liked to have done something a little "cleaner" rather than having a dozen ball valves staring at you, but when you are in a bind and have the nearest big box 30 minutes away, you kinda make due with what you can get.

Ya, things have changed in the world of hydronics in 15 yrs. I still get some trade mags, and see all of these nifty valve/drain combinations, pipe/fittings/equipment. Wish we had those valves back in the 70's.

 

[themaddhatter]

I may be goofy(hell, I know that I'am) but on your water to air exchanger,you want inlet on the bottom,outlet on top to get proper flow. Scott

In a water to air exchanger (talking the style that are horizontal in a plenum), if you are pulling the most heat out of it, you would want the inlet on the top, so that as the water is forced through the exchanger with heat being scrubbed off before it gets to the bottom (closest to the fan).

If you have hot water coming in the bottom, you are using the hottest water to warm the colder water being discharged out the top.

I think that is how it goes....

Anyways, spent the weekend rebuilding the OWB door, got it on as sun set this evening. Threw some wood in, got it running, and house is in the 70s now. I am glad it has been in the 40s here in Minnesota.

Will get pics of door tomorrow when there is light outside.

 

[Iska3]

In a water to air exchanger (talking the style that are horizontal in a plenum), if you are pulling the most heat out of it, you would want the inlet on the top, so that as the water is forced through the exchanger with heat being scrubbed off before it gets to the bottom (closest to the fan).

If you have hot water coming in the bottom, you are using the hottest water to warm the colder water being discharged out the top.

+1

 

[mtfallsmikey]

+1

Unless you are going to use one under a counterflow furnace like I have, then you would reverse the connections.

 

[themaddhatter]

Finished rebuilding the OWB door, and got that mounted up.

I am very thankful that the Gods of winter have spared Minnesota for so long

Attached a few pics. Works very well. Ignore the ugly welds...

Considering all I had access to for this was a 4 1/2" grinder, a 1/2" drill and a welder, it came out pretty decent.

Have a little wisp of smoke in one corner, but is substantially better than what it replaces.

Once the heating season is over, I will clean up the welds, paint everything, and slot the bolt holes using a mill.

Also took a look at the furnace - changed the filter, checked the squirrel cage (no dust bunnies), tightened the belt, and adjusted the drive pulley to give max air velocity.

We shall see how we do overnight.

View attachment 216485View attachment 216486View attachment 216487

 

[themaddhatter]

Unless you are going to use one under a counterflow furnace like I have, then you would reverse the connections.

See now you are just going to confuse me :msp_confused:

 

[mtfallsmikey]

See now you are just going to confuse me :msp_confused:

No, not really...a counterflow furnace has the fan/return mounted in the top, blows down thru the furnace...manufactured home furnaces are like this.
How 'bout this....."lowboy" furnace = furnace that has separate supply/return connections/compartments on top of the furnace. "Highboy" furnace has supply in top, return on the bottom side. These are old-school trade terms tho...