critique the design....

Tim Potter

Present system has no return water protection for the boiler, and no high temp protection for the tubing and short cycles durring warmer periods.

see <span style="text-decoration:underline;">"New House Q's"</span> post in control section

Thank You to Mark for a lot of thought provoking help on this.

 

<span style="text-decoration:underline;">Changes to Control/Piping Summary:</span>

 

A call for heat from any of the thermostats operates the respective motorized valve, closing the contacts.

 

Any or all contact closures signals the SR504 to energize the “Position 1” Secondary Circulator, and closes the X-X contacts calling for Burner and Primary Circulator operation on the boiler.

 

To protect the boiler from low water return temp’s, The A3 aquastat’s contacts don’t close until boiler return water rises above 130*. Above 130, the control energizes the  “Position 2” Injection Circulator.

 

This reverse flow injects hot water into the bottom of the Boiler Buddy, slowly raising its temp until the A1 supply aqua-stat opens at 120* and above. The burner stops firing, but the heat built up in the tank can continue to circulate as required. This protects the Tubing from High Water Temps, and the mass of the Boiler Buddy  protects the boiler from short-cycles

 

Any DHW call overrides the Heating side when DHW Priority switch is on.

 

I am hoping this combination should keep the present boiler ‘happy’ for the rest of its life.

 

At that time, a new Mod/Con can be attached either Pri/Sec or 2 Pipe at the Future Connection area.

 

 

P1 Existing Grundfos 26-99 (moved)

P2 New small Injection Pump (Taco 003 ?)

P3 New DHW Circulator Taco 007

P4 Existing 007 Primary Circulator (moved)

A1 Supply Aquastat (opens on temp rise)

A2 Existing DHW aquastat

A3 Return Aquastat (closes on temp rise)

 

 

 

 

 

Piping Summary:

Re-plumb existing zone valves to come off header in a downward direction, and valves are on the supply side of the loop.

 

 

Add ΔP valve in the loop

 

Ok am I missing something or is there something else I should be looking at

 

Thank You in advance for your input

 

Tim

tim dot potter at ymail dot com

 

Mark Eatherton

Should work OK...

Provides protection for the boiler and the floor.



Maybe someone else can see something I may have missed, but looks solid to me.



ME

Jamie_5

alternative

I would consider ditching the injection and using a simple ESBE thermic valve on the boiler to buffer tank loop.  One less pump, simpler electrical, and easier to get rid of when you change to a mod/con.



Also, 80 gallons seems big for a buffer tank.  A 40 gallon tank would provide 332 pounds of water, so a 40 degree rise (for example) would require 13280 BTU.   Add the content of the heating loops and it's even more.  Is your boiler so big that it would only take a few minutes (i.e. < 10) to provide that much heat?



Otherwise, it looks fine to this DIYer.

MarkPFalade

Out of curiosity,

is the Ergo/Turbo max or something similar a better choice? What are the current feelings on these products? How have they been holding up in the field? I look at those two tanks and I want to combine them.

Tim Potter

Good input,

Thank You for the replies.

I'm still thinking about the ESBE, Mark E. suggested that in an earlier post.

The reason I picked 80 gal for the buffer is to be used when the new mod/con goes in.

80 gal = 664 lbs x delta T 10* = 6640 BTU (40k x .93 / 60 = 620 BTU/min x 10 min)

I think I applied the formula correctly



Anything else I am missing?



Tim

NRT_Rob

reverse indirects

make great buffer tanks, as long as you don't want reset or modulation (every demand becomes a domestic demand)



I'd like someone to test their outputs at lower boiler water temps though... sure would be nice to know how far down you can go in boiler temp on those things and still produce good amounts of hot water.

Mark Eatherton

You forgot something Tim....

in your formula, you took the thermal efficiency into consideration, bit forgot to take into consideration altitudinal deration, which is 2% per 1000 feet above sea level.



No biggy, but in your case, it affects the output by around 18%.



ME

Tim Potter

a good reply deserves another question...

Mark, your reply brings up another question.

I am still intrigued by the Ray 200i. If we eventually went with something that big,

200K @ 93% = 186K on high fire, 40K @ 93% = 37K on low fire.

De-rate at 9000 ft is 18%. High fire goes to 152K does the low fire De-rate also, or is it still 37K on low ?



Thank You;



Tim

Mark Eatherton

They BOTH go down....

It is based on atmospheric density.



Normal deration for atmospheric appliances is 4%/,1000'.



Due to the fact that these beaut's CRAM the air input into the combustion chamber using DC/ECM technology motors, their derate is less, but still present, nonetheless.



Our gas at this altitude is also derated in some cases (east slope Excel Energy gas has air mixed into it to derate it), so it becomes tough to fire at full rated capacity, although there is some 1,000 btu/cubic foot gas available on the western slope (Edwards Colorado).



You're welcome.



ME