I did a quick hack job with MS paint on your drawing. This may be the cheapest route, no zone/ebv required.
As goose points out there are soooooo many ways to do this…...
pump 1 and 2 run when heating with garn, pump 2 and 3 run when heating with burnham
That is another way to do it, and it would work, but you are still pumping through the HX when runing on the BH. Also you need to look at the pump flow directions, remember that you want counterflow through the HX…
another option, simple parallel circut only one pump needed when running burnham. flow checks are needed in both burnham pump and HE pump
Very nice… A variant on what I was doing with my suggestion #2, except I was using zone valves and one pump on the house loop side. I think your approach is better Kabbott as it gets rid of the zone valves, and thus would work a bit simpler on the controls, just run the pump for the desired source and leave the other off.
A few things to keep in mind:
1. No heat to hot tub when heating with Burnham.
2. Your drawing shows a side arm for DHW. My concern with this is side arms(at least the one I have) take a long time to heat x amount of water
compared to an indirect tank with a coil inside. This means you will have 2 pumps running for a long time even when no house zones are calling for
heat. Prolly not very efficient for heating DHW.
I will let some of the heating pro’s debate that one.
I suspect it is getting a little “chilly” out west esp at your elevation. I am sure you will love that beast when you get it in service.
Hack away! I can do your drawing. Goose, what do you think, will this work with a modicum of efficiency? I read pumping away after I got conned into pulling water into the boiler rather than the other way around. The system works well, but I know it would work better if done as you suggest.
If this had proper valves, could this be a solution? Also, running back through the boiler is bad because it represents an additional loss of heat?
Yes but you would need only one circ on the system side of the HX. You could also do it really simply by adding a ball valve inbetween your closely spaced tees going to/from the HX. When you want heat from the Garn simply close the valve which would divert system side flow through the HX and back through the Burnham. When You want to run the Burnham only in shoulder seasons simply leave the ball valve open and allow the flow to go directly to the gas boiler, bypassing the HX. Depending on the flow required in the system and the head added by the HX you may be able to get away with the circ you presently have on your system doing all that work. I think that I would at least try it that way unless you want to have some type of mechanical/electrical control doing the thinking for you.
Hack away! I can do your drawing. Goose, what do you think, will this work with a modicum of efficiency? I read pumping away after I got conned into pulling water into the boiler rather than the other way around. The system works well, but I know it would work better if done as you suggest.
Not sure which idea you mean by “this” but I think any of either my ideas or Kabbots would work very nicely once tuned up a little. Heaterman’s idea of putting a ball valve between the tees of your first drawing would work if you didn’t want the automatic switchover between the two sources.
If you do want the switchover, I think Kabbot’s idea in Post #32 is the simplest and neatest once you get the pump directions and such fixed properly.
Here is my latest drawing based on Goose and Kabbot’s ideas. Is this a possible solution and does this provide for an option to use my Tekmar 356 to control the Burnham as a backup? Also, am I correct in my belief this corrects my “Pumping Away” problem?
This looks better!
You should add where your expansion tank is located so we can give input on PONPC.(pumping away)
Also you still show both sides of heat exchanger flowing the same direction. Minor change, one side should flow the opposite direction.(counter flow)
House side 26-99 on heat exchanger needs flow check.
Couple things, the E/T should be on the other side of the burham pump. This will put PONPC at the inlet of both pumps.
Other thing is that the flow checks should be after the pumps I think( if there not built into pumps) That way they will not
restrict the inlet of the pumps.
Not familiar with your tekmar control but when the garn is to cool for heat you want to switch to the burham pump and turn on the
burner. Lots of ways to do that too.that may be a whole-nuther diagram
Yes, diagram in post #43 looks pretty good. Only change I might make is to put the ET on the line going into the BH in order to put the PONPC closer to the HX pump, but that is relatively minor - it might be worth asking the “guys that get paid for this stuff” about that… It might also be worth putting an air and / or dirt separator on the house loop some place that always gets flow - say on the red line between the lowest “L” Tee, and the Tee where the HX and BH come together.
The custom is usually to put a spirovent or equivalent at the junction with the ET, and that usually works well enough, but with this setup, the ET is only going to get actual flow past it when the BH is running… The other option might be to put the ET on the blue line between the “L” and HX tees - that way it would always see flow, and would work in terms of pumping away, but I don’t know if it’s the best for air separating…
