LL AA-220 Relocation

I think u should insulate the boiler and piping better to be able to put MORE heat into the exchanger rather than into the basement.

But yes theoretically a bypass could temper the water through the heat exchanger, you could also slow your blower fan down?

StokerDon wrote: ↑

Fri. Sep. 28, 2018 5:10 pm

If you delta is 40 degrees, a bypass might help but that's a lot of temperature drop. Sounds more like your burner isn't able to keep up. That's if the 40 degree drop is constant over a long run. Limiting heat loss will help a lot too.

Is this heat exchanger in the house, or an outbuilding?

-Don

Don, the exchanger is in the house in the duct. When this was installed the installer was concerned about restricting the blower so he and the supplier came up with a coil that is larger than the duct and i'm finding out now that the added surface produces a large temp differential. Thought about trying to cutting a piece of sheet metal with a window in it and slipping it in front of the coil to restrict the surface are of the coil? It is a monster! Any other suggestions?

hotblast1357 wrote: ↑

Fri. Sep. 28, 2018 5:44 pm

I think u should insulate the boiler and piping better to be able to put MORE heat into the exchanger rather than into the basement.

But yes theoretically a bypass could temper the water through the heat exchanger, you could also slow your blower fan down?

I am going to put the blower on the slowest setting and see what happens. Also need to insulate the refractory lid to keep more heat in as stated, along with insulating the pipe and pex. Still having some growing pains but nothing should compare to what we went through last winter setting this up! This year I just want to start maximizing efficiency as much as I can. What do recommend to lay on top of lid? Is there a blanket I could use? It IR gun reads about 180* when I hit it while it's running.

Here is the pic of that cracked grate. Is it okay to run?

I can’t comment on the grate, insulate all you can.


And I vote yes for a restrictive plate on the heat exchanger.

swyman wrote: ↑

Sun. Sep. 30, 2018 4:49 pm

Thought about trying to cutting a piece of sheet metal with a window in it and slipping it in front of the coil to restrict the surface are of the coil? It is a monster! Any other suggestions?

Having a coil a little bigger than what you need is a good thing. I'm not sure blocking the airflow over part of it is a good idea. Slowing the fan down to the point where you get a 20 degree delta would be the best bet, but might not be easy.

Another thing you can try is to throttle the water flow to it. Keep dialing it back until you have your 20 degree delta. Hopefully there isn't anything in series with it?

swyman wrote: ↑

Sun. Sep. 30, 2018 6:12 pm

Here is the pic of that cracked grate. Is it okay to run?

A cracked grate is not good. Air will come out of the crack increasing the temperature in that part of the grate making the crack bigger until it fails. I have no idea how long this type of grate will last under those conditions.

-Don

Hello Swyman,

I purchased a full sheet of high temperature furnace insulation from McmasterCarr for under $30.00 my keystokerKAA-4-1 boiler and it made a night and day difference keeping the heat in the boiler.

The part number for the high temperature sheeting is 9356K11 and it cost me $26.47 with shipping and paid with a personal check in August 2016. They accept plastic money and bank money orders too.
The finished sheet size is 24 inches wide and 8 feet long and it is easy to cut to size with a square and a carpet knife if you lay it on some plywood.

Don't worry if the boiler lids stick up a little due to the insulation thickness. The insulation will settle down and it will be fine.

StokerDon wrote: ↑

Sun. Sep. 30, 2018 8:04 pm

Another thing you can try is to throttle the water flow to it. Keep dialing it back until you have your 20 degree delta. Hopefully there isn't anything in series with it?



-Don

I have 3 loops and installed a Taco circulator controller that has a priority loop so when the house calls for heat the other 2 loops are shut off till the house thermostat is satisfied. My house fan is only a 3 speed so I will be sure that it is on it's lowest setting. I guess I will play around with that bypass in that loop to bring my differential closer together and see what happens. On a side note hotblast worked with me for a couple weeks straight getting the wiring correct and also he came up with the idea of adding a strap-on aquastat that when my supply gets to cool (I think is set to 155* on, 180* off) it fires the house furnace which helps the boiler recover quickly. The boiler can maintain the load most of the time but those high wind cold conditions, it will get overloaded and this setup worked well to help the boiler automatically when needed. Not ideal I know, but every year with the help of this forums members, my system keeps getting better!

StokerDon wrote: ↑

Sun. Sep. 30, 2018 8:04 pm

Another thing you can try is to throttle the water flow to it. Keep dialing it back until you have your 20 degree delta.

Sorry swyman, I think I got that backwards. I think throttling the heat flow to the heat exchanger will actually increase the delta.

-Don

Yep...
Speed up the gpm or slow the fan speed...

StokerDon wrote: ↑

Mon. Oct. 01, 2018 7:44 pm

Sorry swyman, I think I got that backwards. I think throttling the heat flow to the heat exchanger will actually increase the delta.

-Don

Don, wouldn't his also hold true in throttling the boiler bypass? It does make sense that if I were to slow the flow going through the coil then it would have more time to cool off....if that makes any sense? So my best scenario would be to slow the fan and run that circulator on high? If my delta is still too large, what would be the next step? HB suggested last year that I run with circulator on high but we didn't slow the fan down. I am just very confident that my delta will still be too large but will have to wait and see.

The main reason for a 40 degree Delta-T is likely to be that you have too many "users" on the zone. But what's wrong with a 40 degree Delta-T? Your boiler isn't cast iron.

In my opinion the "real reason" for 20 degree delta-T as the "ideal" was mainly contrived to make the math simple and in effect dumb it down for the installers. And the "good reason" was to avoid boiler shock. And as all real/good reason things go, only the good reason is disseminated.

I will admit though that if there is another "real reason" for the 20 degree Delta-T it is that with a 40 degree Delta-T, the radiant "users" at the tail end of the zone loop will not be seeing as much heat as you initially calculated them to see, potentially leading to some cold rooms in that section of the house. One potential fix for this is to reduce the size (or length) of the radiators at the beginning of the zone loop and increase the size (or length) of the radiators at the tail end of the zone loop, such that the overall "user" demand on the loop is the same as before (so you still end up with 40 degrees of Delta-T), but the distribution is modified to accommodate this Delta-T and provide for room to room heat uniformity. This practice also has merit for any other Delta-T, including 20 degrees.

lsayre wrote: ↑

Tue. Oct. 02, 2018 9:09 am

The main reason for a 40 degree Delta-T is likely to be that you have too many "users" on the zone. But what's wrong with a 40 degree Delta-T? Your boiler isn't cast iron.

In my opinion the "real reason" for 20 degree delta-T as the "ideal" was mainly contrived to make the math simple and in effect dumb it down for the installers. And the "good reason" was to avoid boiler shock. And as all real/good reason things go, only the good reason is disseminated.

I will admit though that if there is another "real reason" for the 20 degree Delta-T it is that with a 40 degree Delta-T, the radiant "users" at the tail end of the zone loop will not be seeing as much heat as you initially calculated them to see, potentially leading to some cold rooms in that section of the house. One potential fix for this is to reduce the size (or length) of the radiators at the beginning of the zone loop and increase the size (or length) of the radiators at the tail end of the zone loop, such that the overall "user" demand on the loop is the same as before (so you still end up with 40 degrees of Delta-T), but the distribution is modified to accommodate this Delta-T.

I'm all coils, main coil is in the house furnace duct, 2nd coil is in the garage and usually pulls about 5-8 degrees delta, and the barn coil. I run 2 circulators off a Taco controller that has priority zoning and my house coil is set on priority so the other circulator shuts off when main calls for heat. My concern for my delta differential is the boiler won't keep up with the main coil if the furnace fan cycles too long. I was thinking if I could reduce the delta the boiler could possibly keep up? My main coil is grossly oversized which was why I brought up the question of installing a blocking plate on the coil to reduce it's surface area which in theory reduce my delta?

The 40 degree Delta-T you are witnessing has absolutely nothing to do with the boiler being able to keep up or not. The boiler is not causing the 40 degree Delta-T. And your combined home and outbuildings overall maximum calculated heat demand (or load) on the coldest day of the year is not altered in any way, shape, or form as a consequence of the 40 degree Delta-T.

Quadruple the boilers output (by purchasing a 4 times larger boiler) and that zone will still have a 40 degree Delta-T.

In my opinion if your boiler was properly sized for the coldest day of the year you are chasing a non-issue.