SideArm plumbing

[McKraut]

I'm looking at adding a side arm to the new boiler set up. I have a few questions I'm hoping you can asnwer for me.

1. My understanding is that I will need a circulator to bring the heat to the sidearm from the boiler. Why don't you use a circulator to move water in the HWH through the sidearm too? I would think that it would decrease the tank's recovery time significantly. Could you set up a relay that would power both circulators when the HWH calls for heat?
2. Maple1 stated in another thread that he had problems with his sidearm stealing heat from his system because his piping was 1 inch. Can you bring that down to 3/4 inch without a problem (it would be 3/4 piping supplying the sidearm). I did not see any sidearms that were 3/4 inch for both boiler and DHW piping.
3. I've seen in shown 2 different ways. Does the supply from the boiler go into the bottom or the top of the sidearm? I wouldn't think it would matter if you are using a circulator, but wanted to double check.
4. Any preference for copper or stainless steel?
5. Is double walled worth the price? We do not have stringent building codes here, but I don't want to cut corners if the money is well spent.

Thanks for your insight,

Bob

 

[maple1]

I'm looking at adding a side arm to the new boiler set up. I have a few questions I'm hoping you can asnwer for me.

1. My understanding is that I will need a circulator to bring the heat to the sidearm from the boiler. Why don't you use a circulator to move water in the HWH through the sidearm too? I would think that it would decrease the tank's recovery time significantly. Could you set up a relay that would power both circulators when the HWH calls for heat?
2. Maple1 stated in another thread that he had problems with his sidearm stealing heat from his system because his piping was 1 inch. Can you bring that down to 3/4 inch without a problem (it would be 3/4 piping supplying the sidearm). I did not see any sidearms that were 3/4 inch for both boiler and DHW piping.
3. I've seen in shown 2 different ways. Does the supply from the boiler go into the bottom or the top of the sidearm? I wouldn't think it would matter if you are using a circulator, but wanted to double check.
4. Any preference for copper or stainless steel?
5. Is double walled worth the price? We do not have stringent building codes here, but I don't want to cut corners if the money is well spent.

Thanks for your insight,


Bob

I can try to offer a bit more feedback from trying to get mine working better in non-heating season.

1. The beauty of a sidearm is being able to simply heat the DHW with convection flow & little added pumping. There is a trade-off though. I've only had temp sensors on mine for not quite a week, but it's pretty evident that they (or at least mine) don't get all the heat out of the supply that could be gotten by other means. If you pump the DHW through, it won't get as hot as slower convection flow. I'm not sure all my sensors are working right, but am seeing the DHW out get to within only about 20° of hot supply in. If you're considering a pump on the DHW side for faster recovery, you'll likely need to go to a flat plate HX rather than use a sidearm. But then you'll lose the convection ability.

2. I have the zone valve in my sidearm circuit now wired to my main 15-58 load circ. via the endswitch. It pumps way too much - I am only seeing about a 6 or 7° delta T through the A side of the sidearm, and it's screwing up my stratification big time. It is also diverting too much flow from the loading circuit when charging storage. I am now planning on swapping the 15-58 ASAP for an Alpha and choking down a ball valve on the DHW return piping. I had considered an Alpha when I did my system over, but not seriously enough. I didn't know much about them, just recently heard about them, and the supplier I was using then for most of my stuff didn't carry them. This circ also does the 4 heating zones. This should make a big difference in how long I can go on storage heating the DHW, and also maybe tend to pull less water though the cold boiler.

3. My supply goes into the top.

4. Mine is copper - the short multi-tube kind. No input on stainles, but I'm curious about them.

5. No input there either, I'm still new at the sidearm thing. Likely a good idea, but I don't really know about the durability of these things.

One further thing I'm also considering - getting another identical sidearm & doubling it up with my current one (on top of it). I would really like to see a smaller difference in my DHW out and hot supply in - or get more heat out of my supply water. That configuration would fit my space quite well with minimal re-piping. The main thing to get right with these things is their location w.r.t the inlets & outlets of your DHW tank. Get it as low as possible (like right on top of the bottom DHW tank fitting you'd use), and don't go sideways with it, or go as little as possible. Mine is off to the side a foot or so due to mounting possibilities - I'm getting decent flow through it but it would be better if it was right on top of the bottom fitting.

 

[heaterman]

Regardless of whether we are using a sidearm type HX or a little 10 plate, we pump both sides and control both pumps with an aquastat on the water heater side of the piping. Really simple and pretty bulletproof. All you need for a circ is a small one like what is commonly used for hot water piping recirculation.
We just piped one up for a customer about 3 weeks ago using a 5x12-10 plate HX. It took his 40 gallon tank from ground water temp (43-45*) up to 140* in about 15 minutes. No more running out of hot water when all the chillin are in the tub and mom is doing laundry at the same time.

 

[maple1]

Curious as to the exact make/model of DHW-side circ you use? I don't seem to have access to many options here.

I'm still of the opinion that as long as the sidearm is plumbed right so it works the way it is supposed to (convection flow), a circ would add little to the DHW side as the sidearm just doesn't seem to have the heat recovery ability that a flat plate does (no direct experience with a flat plate, just going by what I've read about them on here). As it is now with mine, with slow convection flow I'm still seeing about 30° between DHW out & hot supply in (I've got a temp sensor I think I'll double check though). If I was to do it all over again, I might do flat plate rather than sidearm - but I do really like convection flows. Still weighing adding another sidearm vs. replacing with flat plate, actually.

 

[Armaton]

Heaterman, I also would appreciate the pump model, and design for the dual pump system. I was going to use the on demand style with a 30 plate, but the system you described above seems much easier and more effective.

Brandon

 

[McKraut]

Thank all of you for your help. If Heaterman can give us more details I would appreciate it too.

 

[maple1]

After a bit of googling, the B&G Ecocirc looks pretty interesting.

 

[maple1]

Hoping to pick up my new Alpha tomorrow. While there, I'm going to ask about the Ecocirc.

Anybody know off the top of their head how much head a FPHX presents to a pump? Say either a 10 or 20 plate, 5x12? My searching time is short between now & then...

 

[Bob Rohr]

Hoping to pick up my new Alpha tomorrow. While there, I'm going to ask about the Ecocirc.

Anybody know off the top of their head how much head a FPHX presents to a pump? Say either a 10 or 20 plate, 5x12? My searching time is short between now & then...

 

[Bob Rohr]

the pressure drop "head" is directly related to the flow rate you want to move thru the HX. It varies from size to size, but 8-10 gpm thru a 20 plate 5X12 will be within what an Alpha or Eco will handle, assuming you are using water not a glycol mix.

 

[heaterman]

Thank all of you for your help. If Heaterman can give us more details I would appreciate it too.

Well I have it all drawn out but I can't get this CAD program to translate it into a format that will post here. Has to convert to a jpeg file and doesn't seem to know how to do it.....or rather, maybe I don't know how to do it....
I'll keep trying.

 

[NE WOOD BURNER]

What version cadd you running?

You can always print to a .pdf if the driver is installed. or use free pdf995 free installs like a printer

 

[maple1]

Just finished swapping in the new Alpha for the 15-58 load circ an hour ago. Got into a bit of a pinch I wasn't expecting with my piping wanting to squeeze together in the pump space, but I made quick use of a tie down strap and all is good.

This thing is sweet - almost makes me want winter to get here again so I can make full use of it. I have the ball valve in the sidearm return pipe at least 3/4 closed, and the Alpha quietly throttled itself down to 1gpm at around 15 watts. With that tiny flow I am still seeing full supply heat temps on my sidearm A-in (currently 160°), with a delta-T of now around 10° (from 7°). The approach on the DHW-out is still around what it was before - around 30°. In other words, not all that good, exchanger-wise. But at least now I'm not messing up my stratification as fast as I was before. I am still waiting for the correct Johnson A-419 to get here to get the control part properly set up & dialed in - the sidearm actually functions not too bad as an on-demand heater. Even when the DHW-in drops from the preheated temps, down to the 60's (some people here like long showers), the DHW-out seems to stay within 10° of the 30° approach. Which seems odd to me, but that's what my thermometers are telling me.

Next on my list is check out a pump to add to the DHW side - I left the info sheet for the Ecocirc at the supplier for them to use to see if they could get me a price on it. Depending on how that works, I may or may not then spring for a flat plate. If I was going to burn all summer for DHW, that would likely be a definite - I have concluded so far that sidearms (or at least this one) are not very good for heating DHW from storage when not burning/heating due to the wide approach & narrow delta-T I'm seeing. But with the way the heat comes off the smoke pipe when burning, and hangs around the house for days when it's 80° out - I don't think I'll be burning that much in the summer time. It was HOT today...

 

[McKraut]

Well I have it all drawn out but I can't get this CAD program to translate it into a format that will post here. Has to convert to a jpeg file and doesn't seem to know how to do it.....or rather, maybe I don't know how to do it....
I'll keep trying.

I appreciate the effort. I will check back to see if it shows up.

Bob