will this work

  • Active since 1995, Hearth.com is THE place on the internet for free information and advice about wood stoves, pellet stoves and other energy saving equipment.

    We strive to provide opinions, articles, discussions and history related to Hearth Products and in a more general sense, energy issues.

    We promote the EFFICIENT, RESPONSIBLE, CLEAN and SAFE use of all fuels, whether renewable or fossil.
Status
Not open for further replies.
huffdawg

huffdawg

Minister of Fire
Oct 3, 2009
1,457
British Columbia Canada
I want to tie in my eko 40 to the existing system which is the green colour. The red color is what id like to do if it will work. Id like to have it wired so that when the eko is running the lpg boiler shuts off and the two zone valves close so that I dont get flow through the lpg boiler.
I Am not sure if the left zv is needed or not.
I have tested the system with lpg boiler shut off and everything is still operational except the p/p below the lpg boiler

Cheers Huff
 

Attachments

  • 100_6699.jpg
    100_6699.jpg
    104.3 KB · Views: 737
my thoughts, on a call for dhw you have two pumps in series, doubling the head. Probably not a huge deal depending on the size of the HX coil in the tank, you will have some high velocities, and eventual wear.

When there is a call for heat and DHW together how much flow goes where?

On a call for heat the flow could just divert around through the DHW?

Can it operate with both boilers firing for high demand and not much wood fire.

In this drawing you have 5 pumps and two zone valves and still some un-predictability. Also a wiring and control challenge.

With a true P/S, shown here you would have 6 pumps, no zone valves and 100% control and predictability.

hr
 

Attachments

  • Picture 12.png
    Picture 12.png
    118.8 KB · Views: 614
Hi IHW, the existing system is pretty much there to stay the way it is for a couple years at least . Is my system not a true P/S. The only anomoly being the DHW side. The dhw p/p is a 3 speed pp should that not offer a means of controlling speed.
I would like to do it the way you suggest but that would mean an almost total replumb of the system that is already working good. It is plumbed as per Buderus Boiler piping diagram and by a qualified tech.
I am hoping someone like nofossil will chime in with some help with the control or anyone with some good savvy in that dept.

Thanx Huff
 
To have a P/S piping you need closely spaced tees. I think you have that covered where the GB ties into the lower loop.

I suspect that you will always have some flow through the DHW loop when the EKO is running. It depends on the pressure drop through the GB hx based against the pressure drop through the DHW coil. Do all the pumps have integral check valves?

For insurance install a thermostatic mix valve on the DHW tank output, that tank may get to 180F or whatever the EKO runs up to. That could be a dangerous wake up call at a faucet!

I think that loop that the GB flows into should be split between where the infloor returns into and the baseboard return, or the baseboard return goes to the cold side of the radiant mix valve?.

This is a true hybrid piping :) The GB is tied into the inner loop via P/S. The EKO is parallel to the DHW loop. The DHW loop is parallel to the GB.
The EKO to heating loop changes based on the zone valve position. You may need some check valves to keep all the flows on the right path.
 
huffdawg said:
I want to tie in my eko 40 to the existing system which is the green colour. The red color is what id like to do if it will work. Id like to have it wired so that when the eko is running the lpg boiler shuts off and the two zone valves close so that I dont get flow through the lpg boiler.
I Am not sure if the left zv is needed or not.
I have tested the system with lpg boiler shut off and everything is still operational except the p/p below the lpg boiler

Cheers Huff
Click to expand...

[Have redrawn but I believe original piping is all still the same.]

You should be able to pull through the existing LP boiler circ downstream of the DHW return if you add a checkvalve before the LP.

Need a flo-check in WOOD return to prevent LP pushing through WOOD circ when LP circ active and WOOD circ not active.

Not drawn: maybe need a flo-check in DHW loop to keep either LP or WOOD from pushing through DHW circ.

--ewd
 

Attachments

  • tie-in.jpg
    tie-in.jpg
    23.3 KB · Views: 626
ewdudley said:
huffdawg said:
I want to tie in my eko 40 to the existing system which is the green colour. The red color is what id like to do if it will work. Id like to have it wired so that when the eko is running the lpg boiler shuts off and the two zone valves close so that I dont get flow through the lpg boiler.
I Am not sure if the left zv is needed or not.
I have tested the system with lpg boiler shut off and everything is still operational except the p/p below the lpg boiler

Cheers Huff
Click to expand...

[Have redrawn but I believe original piping is all still the same.]

You should be able to pull through the existing LP boiler circ downstream of the DHW return if you add a checkvalve before the LP.

Need a flo-check in WOOD return to prevent LP pushing through WOOD circ when LP circ active and WOOD circ not active.

Not drawn: maybe need a flo-check in DHW loop to keep either LP or WOOD from pushing through DHW circ.

--ewd
Click to expand...

That looks like a possibilty EWD the only thing is the control for the DHW is activated from the boiler , I wired the temp.sensor transducer from dhw tk to a connection on the boiler that tells the honeywell contoller to put the DHW p/p on when there is a demand for hot water. Thats how I think it works

Thanx Huff
 
Does any one know how I can get my Dhw working as per EWD drawing above. I think everything else works normal when the lpg boiler is off, but the dhw p/p does not work when boiler switched off.

thanx huff
 
huffdawg said:
Does any one know how I can get my Dhw working as per EWD drawing above. I think everything else works normal when the lpg boiler is off, but the dhw p/p does not work when boiler switched off.

thanx huff
Click to expand...

Maybe I'm missing something, but it looks like to me that a DHW circ call for heat is no different than a call for heat from either of the other two load circs. If any of the three load circs calls for heat, then the circ for the active boiler has to be pumping to move heat from the active boiler to the load circs.

Just don't ask me how you switch over automatically to the LP boiler when you get snowed-in over at Aunt Kelly's, I don't have that part figured out.

Cheers --ewd
 
ewdudley said:
huffdawg said:
Does any one know how I can get my Dhw working as per EWD drawing above. I think everything else works normal when the lpg boiler is off, but the dhw p/p does not work when boiler switched off.

thanx huff
Click to expand...

Maybe I'm missing something, but it looks like to me that a DHW circ call for heat is no different than a call for heat from either of the other two load circs. If any of the three load circs calls for heat, then the circ for the active boiler has to be pumping to move heat from the active boiler to the load circs.

Just don't ask me how you switch over automatically to the LP boiler when you get snowed-in over at Aunt Kelly's, I don't have that part figured out.

Cheers --ewd
Click to expand...

I think the call for heat is different. the boiler its self controls the dhw the rest of the system is contolled by the honewell controller. the hot water is priority
When I shut the boiler down and then run some hotwater it will not pickup a call for heat and not fire and run the circ p/p .
whereas the rest the system will run normally if there is a call for heat from a themistat. when the boiler is switched off.

thanx huff
 
Does your boiler have the factory supplied injection loop/DHW connection under it? Or did you tech build it him self. If it is the facrtory unit the the chances of you cutting anything in there are slim. You might be better off to have your local heating tech come out and go over the design possibilities with you. i have installed these boilers and If I remember correctly the plumbing of the injection pump/dhw pump manifolds is super compact.
 
sgrenier35 said:
Does your boiler have the factory supplied injection loop/DHW connection under it? Or did you tech build it him self. If it is the facrtory unit the the chances of you cutting anything in there are slim. You might be better off to have your local heating tech come out and go over the design possibilities with you. i have installed these boilers and If I remember correctly the plumbing of the injection pump/dhw pump manifolds is super compact.
Click to expand...

Now that I've seen the manual I'd have to agree. You'd really have to butcher the factory manifold to accommodate my suggested circuit above. Plus the DHW problem would still be messy.

I don't have time to draw it right now, but adding the wood boiler as another secondary circuit that ties into the load return piping the same as the existing gas boiler, as suggested above, would be a possibility.

So as not to mess with the gas boiler DHW controls, for DHW you might want to provide an alternate control with its own sensor on the indirect tank, then tee off the DHW return and provide a zone-valved path to the load return piping upstream of the new closely spaced tees where the wood boiler secondary loop ties in.

It looks like you have a spare pump relay in your zone relay box, the new DHW control would tie in as another demand thermostat and the DHW pump would be activated by the Bulderus control when the gas boiler is active or by the zone relay box when the wood boiler is active. The zone relay box probably has a priority zone you could use for the DHW pump if you wanted to maintain that feature.

Or just let the gas boiler do the DHW heating, it looks like a modern efficient unit so it might not be worth it to fool with the DHW end of it.

--ewd
 
sgrenier35 said:
Does your boiler have the factory supplied injection loop/DHW connection under it? Or did you tech build it him self. If it is the facrtory unit the the chances of you cutting anything in there are slim. You might be better off to have your local heating tech come out and go over the design possibilities with you. i have installed these boilers and If I remember correctly the plumbing of the injection pump/dhw pump manifolds is super compact.
Click to expand...

yes it does , I have a local guy here who is going to tie in the lpg boiler end. But he doesnt have much experience with this sort of scenerio



Thanx huff
 
The tech. that built my system says to tee in the supply on the output side of lpg boiler and the return on the dhw pipe just before it goes into the boiler.
He says just to leave the boiler on and everthing wiil take care of itself

In hot Water , EWDudley, or anyone else that has expertise in this area agree with this?


Cheers Huff
 
huffdawg said:
The tech. that built my system says to tee in the supply on the output side of lpg boiler and the return on the dhw pipe just before it goes into the boiler.
He says just to leave the boiler on and everthing wiil take care of itself

In hot Water , EWDudley, or anyone else that has expertise in this area agree with this?


Cheers Huff
Click to expand...

Sure, that would be the same as my drawing above, except your tech was able to see that tapping into the DHW return is the same as tapping into the boiler return manifold, and he also correctly sees that the check valve I had going into the return side of the boiler is not necessary.

So he's saying go ahead let the wood boiler keep the gas boiler hot so that it runs the load circs for you, but it doesn't need to fire because it's off on high limit. I was reflexively looking for a way to keep from circulating wood boiler water through the gas boiler because of flue losses, but with your type of boiler it shouldn't be a significant problem. And when there's no wood heat, the gas boiler fires up with no additional control logic.

--ewd
 
ewdudley said:
huffdawg said:
The tech. that built my system says to tee in the supply on the output side of lpg boiler and the return on the dhw pipe just before it goes into the boiler.
He says just to leave the boiler on and everthing wiil take care of itself

In hot Water , EWDudley, or anyone else that has expertise in this area agree with this?


Cheers Huff
Click to expand...

Sure, that would be the same as my drawing above, except your tech was able to see that tapping into the DHW return is the same as tapping into the boiler return manifold, and he also correctly sees that the check valve I had going into the return side of the boiler is not necessary.

So he's saying go ahead let the wood boiler keep the gas boiler hot so that it runs the load circs for you, but it doesn't need to fire because it's off on high limit.I was reflexively looking for a way to keep from circulating wood boiler water through the gas boiler because of flue losses, but with your type of boiler it shouldn't be a significant problem. And when there's no wood heat, the gas boiler fires up with no additional control logic.

--ewd
Click to expand...
I would of liked not to push water from the eko through the lpg boiler, but it does seem the easiest way without having to do a bunch of repiping. Its the damn dhw priority thing thats throwing a wrench into the whole thing.
The tech also suggested throwing in a y - strainer before the lpg boiler.

Thanx Huff.
 
ewdudley said:
huffdawg said:
The tech. that built my system says to tee in the supply on the output side of lpg boiler and the return on the dhw pipe just before it goes into the boiler.
He says just to leave the boiler on and everthing wiil take care of itself

In hot Water , EWDudley, or anyone else that has expertise in this area agree with this?


Cheers Huff
Click to expand...

Sure, that would be the same as my drawing above, except your tech was able to see that tapping into the DHW return is the same as tapping into the boiler return manifold, and he also correctly sees that the check valve I had going into the return side of the boiler is not necessary.

So he's saying go ahead let the wood boiler keep the gas boiler hot so that it runs the load circs for you, but it doesn't need to fire because it's off on high limit. I was reflexively looking for a way to keep from circulating wood boiler water through the gas boiler because of flue losses, but with your type of boiler it shouldn't be a significant problem. And when there's no wood heat, the gas boiler fires up with no additional control logic.

--ewd
Click to expand...
Im wondering now if the boiler circ. p/p will still be on if the boilers off on high limit,you would think so?
 
huffdawg said:
ewdudley said:
huffdawg said:
The tech. that built my system says to tee in the supply on the output side of lpg boiler and the return on the dhw pipe just before it goes into the boiler.
He says just to leave the boiler on and everthing wiil take care of itself

or anyone agree with this?


Cheers Huff
Click to expand...

Sure

So he's saying go ahead let the wood boiler keep the gas boiler hot so that it runs the load circs for you, but it doesn't need to fire because it's off on high limit.

--ewd
Click to expand...
Im wondering now if the boiler circ. p/p will still be on if the boilers off on high limit,you would think so?
Click to expand...

I should have said the boiler burner is off on high limit. If the boiler system sees a demand for heat for DHW or any zone, it will run the appropriate pump to satisfy the demand if it has water hot enough for the type of demand, else it will run the burner until the water is hot enough.

The need for the pump enables the burner, but if the water is already hot enough the burner won't fire. Your pro is setting it up so that the wood boiler keeps the gas boiler hot so it can pump and doesn't need to fire.

Typically you want to avoid heating an idle boiler, but that's more of a problem for some big old cast iron oil-fired unit with an eight-inch flue hooked to a cold chimney. Your boiler doesn't look like it will lose much heat up a flue or into the mechanical room. I think you'll be quite happy with your pro's solution.
 
Hi Elliot, im been thinking about this. and im wondering with the the supply from the wood boiler connected on the outlet side of the gas boiler , will the gas boiler high limit sensor still be able to get high enough temps to operate properly.

Thanx Huff
 
huffdawg said:
Hi Elliot, im been thinking about this. and im wondering with the the supply from the wood boiler connected on the outlet side of the gas boiler , will the gas boiler high limit sensor still be able to get high enough temps to operate properly.

Thanx Huff
Click to expand...

It sounded like you local tech had this pretty well figured out, but I don't remember all the details.

I believe to have everything work seamlessly you would need to either run the the wood boiler circulator constantly, or you could run it only when either the DHW PS circulator or the boiler circulator PK is running, which you could do with some additional relay logic.

The other thing that would need to happen is to insure that the wood boiler circ flow exceeds the PS or PK circulator flows so that when either the PS or PK pump is pumping there is some leftover flow through the gas boiler to keep it hot enough so that it doesn't fire. You could do this maybe by using the low speed of a three-speed pump or by throttling the PK flow with the valve adjacent to it, although in theory using a ball valve for throttling can wear out the valve.

Once you've ensured that some minimal amount of hot wood boiler water is flowing through the gas boiler it's just a matter of adjusting the DHW and space heating setpoints on the gas boiler low enough to keep the gas boiler from firing.

--ewd
 
Status
Not open for further replies.

Similar threads

P
Dodging a bullet with my heating system
Replies
0
Views
951
The Boiler Room - Wood Boilers and Furnaces
peakbagger
P
P
Time to label the valves
Replies
1
Views
405
The Boiler Room - Wood Boilers and Furnaces
hedge wood
H
Z
Running LP and Wood boiler
Replies
0
Views
484
It's a Gas!
zero2491
Z
Ashful
Pyrolysis... and setting your house aflame
Replies
56
Views
3K
DIY and General non-hearth advice
EatenByLimestone
EatenByLimestone
M
Finally found a solution to my short burn times and my fire going out.
Replies
4
Views
519
The Boiler Room - Wood Boilers and Furnaces
mjstef
M
Top Bottom
Back