New England SteamWorks Could Use Some Help With Solar Install!

New England SteamWorks

I know, I know. What are we doing with solar?!

Sigh...The customer was to have a solar hot water system installed. We were to follow and replace his steam boiler, and then connect a hot water loop to the boiler coil of the solar tank.

But naturally when we arrive the solar tank is in the garage uninstalled, the solar guys are busy elsewhere, the customer now has no hot water, and guess who's to blame in this no-win scenario?

Having never contemplated solar, we are doing a bit of head scratching. We figured with everything else installed it would be easy enough to figure out. But with nothing installed, not so much.

We've attached a photo and the piping diagram, but naturally it's for a hot water system. We don't understand why there are two circulators together in tandem in photo (doesn't seem likely it would ship this way), and we do not understand how the system is supposed to switch between boiler and solar.

Can we just pipe directly to the boiler coil inlet and outlets like a standard indirect?

Does the Resol control operate our circulator?

Any help greatly appreciated.

mattmia2

Maybe the circulators in tandem were just for shipping?

Jamie Hall

That, Ryan ( @New England SteamWorks ) makes the piping for a nuclear submarine look simple. And gives me a headache.

It's also one of the worst piping diagrams to understand I've seen in a few decades. However... a few comments.

First, over on the far left side it looks from the diagram as though there are two pipes coming down verrtically and then one pipe going into the boiler. We both know that isn't going to work... and on very close examination what I think I see is a pipe flowing downward with a circulator on it. It looks as though that pipe Ts into the one going into the boiler, but I think not. I think that goes into the boiler in back of (hidden!) the other pipe coming out. If that is true, then those two pipes are part of a primary loop which goes up and then the boiler output line turns horizontal (no, I don't know why it goes left, then up again, then right...) and has the expansion tank on it (in the wrong place, but let that be...). Or it would be a primary loop if there were a connecting line at the far end of the two horizontals. There isn't, and I don't know why. Then the lower of the two horizontals is the return to the boiler. The three zones -- two heating and one for the DHW indirect -- take off of that each through its own circulator.

So. Puzzle one. Why doesn't the diagram show a closed primary loop? I have no idea. The Ts aren't properly spaced, either. Humph.

The solar side is straightforward enough. It's not a drainback system, though.

That help any?

New England SteamWorks

I can only think if you shipped like that you would have a lot of damage, so I think not.

mattmia2 said:

Maybe the circulators in tandem were just for shipping?

New England SteamWorks

Only in the sense that misery loves company and I no longer feel alone!

Jamie Hall said:

That help any?

EBEBRATT-Ed

It is a funky drawing but I think it is basically ok.

On the left side of the boiler down low it looks like bot pipes are teed into the same pipe....they are not, the return is directly behind the supply. If you look close there is onlt 1 tee you can see but no matter your on steam.

There going to switch over (between boiler and solar) by stopping and starting the solar or boiler loop pump

I would just pipe the indirect as you would any indirect with a steam boiler.

Boiler water in and out of the indirect with a bronze pump and assorted valves

Or

you can heat the indirect with a tankless or another heat exchanger but you would need a standard circulator and expansion tank, PRV for water feed etc

New England SteamWorks

Thank you Ed. The owner is under the impression (and it makes sense) that the solar system switches automatically to boiler if solar insufficient. We are not sure how that is supposed to happen, but it definitely will not happen if we do it like a standard indirect.

Any thoughts on the tandem circulators?

New England SteamWorks

The two circulators are wired together and wrench-tight. Must be the solar guys installed them. Has anyone seen this tandem set up? Or are the solar guys lost in space?

Resol Control:

Jamie Hall

Only thing I can think of is that for some reason they needed more head than one could provide, and did it that way... but they are not piped on that tank quite as shown on the diagram...

Lost in space. Definitely.

EBEBRATT-Ed

Putting two pumps in series will give you the same GPM at double the head.

so a pump rated 10 gpm@ 10' of head two of those pumps in series will give you 10gpm @20' of head

EBEBRATT-Ed

I guess when they want solar they would turn the solar circ on and shut your indirect pump down.

How are they going to keep the solar loop from overheating would be my concern?

There is no ON_OFF switch for solar

DJD775

Not a pro but the solar portion of the tank should have a sensor on the lower section of the tank and external sensor on the solar panel. The solar pump should only run when there is sufficient heat in panels and the lower aquastat is calling for heat. If there is not enough solar heat to satisfy the call the upper aquastat that controls the boiler will eventually kick in and activate the boiler circ.
The Resol unit looks like the solar control module that should connect to both the tank and panel sensors.

Might be an inspector issue since you are a pro but I would think you could just plumb the top coil to the boiler and wire as an indirect and leave the solar portion up to the other installer if he ever shows up.

Zman

Drainback solar systems sometimes use 2 circs in series like that. One circ will only run for a few minutes until the "Ferris Wheel" is established. Is there a timer relay on one circ? What type of panels? Did they come with a vent?

Zman

Someone needs to pull @hot_rod out of his fancy new shop so he can educate us

GW

"who's to blame"...you're trying to help them and you're catching flak?? Give me their phone number 😁😁😁

I wish you luck with that control station. We did a Viessmann set up like what you're doing now years ago. The logic for the control was wild, the manual was very difficult to digest. Haven't done one since; nor do i ever wish to touch solar again.

I suspect the two pumps are meant to be separate, one for the solar loop and one for the hydroponic loop.

Yes, that drawing seems semi painful, (I dig that jiggle above the boiler), but essentially the control is shutting the boiler off IF there's enough heat in the solar tank.

Good luck

EBEBRATT-Ed

@GW that is true but I believe he is working with a steam boiler

GW

Ed OK I didn't catch that part.

Larry Weingarten

Hi, I'd expect that this was designed as a drainback system or there wouldn't be stacked pumps. The piping diagram doesn't fit that thinking though. Are you sure that you have the correct diagram? Is there a drainback tank lying around? Perhaps a call to the solar guys could clear up some of the mystery. A basic question, is this just for DHW or is it supposed to help with space heating as well? That schematic seems far more complex than it needs to be. A standard differential control or even an aquastat can do the switching between solar and backup heating. I'm sorry if I'm missing something obvious, but we're troubleshooting here, so I don't want to make any assumptions.

Yours, Larry

ps, What is a relief valve doing down at the bottom of the tank screwed into what looks like a black iron cross? Questions!!

JDHW

Looking at the tank picture is looks like and indirect tank that has two coil connections for heating that are at different levels the upper ones for boiler input and the lower ones for solar. So from your perspective just pipe the upper pair to the boiler and control the boiler with an thermostat at the port just above this coil. If there is no solar input this is just an indirect with a smaller active volume than the tank size. When there is solar input the water will be warmed and there will a reduced requirement for boiler or maybe no requirement for boiler input. Customer should be happy with a working hot water system.

Solar people need to sort out getting heat to the bottom of the tank and dealing with excess input when the tank can't take the heat.

If you fit the boiler controls with a timer the customer should be advised to heat up the water when there is no solar input (i.e at night) so max gain from the solar. This assumes the tank is big enough to store hot water for a days consumption to maximise solar gains.

John

mattmia2

Larry Weingarten said:

ps, What is a relief valve doing down at the bottom of the tank screwed into what looks like a black iron cross? Questions!!

Relief vavle for the solar part of the system? Although there are numerous valves between it and the collector, but what about the coil in the tank, you could valve that off and heat it from the boiler.

mattmia2

JDHW said:

Looking at the tank picture is looks like and indirect tank that has two coil connections for heating that are at different levels the upper ones for boiler input and the lower ones for solar. So from your perspective just pipe the upper pair to the boiler and control the boiler with an thermostat at the port just above this coil. If there is no solar input this is just an indirect with a smaller active volume than the tank size. When there is solar input the water will be warmed and there will a reduced requirement for boiler or maybe no requirement for boiler input. Customer should be happy with a working hot water system.

I thought some of the superstores with dual coils had the 2 coils intertwined such that the 2 ports at the bottom connected to 2 different coils but I don't see the picture of the one that I was thinking of on their web site anymore.

mattmia2

I think HTP's instructions want to see brass or stainless on the nipples welded to the tank.

New England SteamWorks

Update: We insisted that the solar guys come back and at a minimum hook the tank to the domestic water side before we did any solar work. So they are supposedly doing that now and we plan to return Monday. We've had a call in to HTTP for 2 days running, and no call back from their tech guys, so that operation needs an overhaul...

As of now, we are just going to use the two middle tappings and pipe it exactly as we would with a standard indirect, using a standard aquastat, and ignoring all their controls and parallel circulators.

mattmia2

mattmia2 said:

Larry Weingarten said:

ps, What is a relief valve doing down at the bottom of the tank screwed into what looks like a black iron cross? Questions!!

Relief vavle for the solar part of the system? Although there are numerous valves between it and the collector, but what about the coil in the tank, you could valve that off and heat it from the boiler.

I think this is actually an interesting question. Does the tank coil require a separate relief valve on the coil from the relief valve on the boiler because it could be valved off from the boiler and the water in the coil could be heated from the solar source through the DHW in the tank.

JDHW

I think what you are proposing is all that is required for the final solution. Cold water at the bottom of the tank will get heated by solar input and rise up the tank. If it is hot enough the boiler will not fire up and it is not, the boiler will fire up and heat the contents at the top of the tank to the required temperature. No solar input and it is just a standard indirect tank.

hot_rod

How many collectors and what type? Unless you have 4 or more I would skip the heating interface, just not worth the piping and expense. Best way to integrate with heat is a 3 way zone valve, use the heat from the tank first, then the boiler.

If you don't use the upper coil for heating, you could series pipe the upper and lower coils, more HX surface.

Dual pumps are usually for drainback, that Resol control has then option to wire for drainback, a pump to R1 and R2. IF you have a large array you will want a drainback or the whole system will stagnate a lot in the summer, destroy the glycol, etc..

For domestic, cold in bottom, hot out top to water heater. S1 sensor1 in collector, S2 at or near bottom of tank near bottom of tank.

The drawing is accurate, hard to read without color.

Here is how a common solar combi system pipes with a 3 way valve. That Resol control will power a 120V 3 way valve and it runs this entire system.

First decide if it will be drainback or glycol, based on the array side. I'd be glad to talk you through the control settings and best piping.

New England SteamWorks

I guess another question is: Should we set up our boiler side as cold start? Or maintain a boiler temp with a boiler aquastat? I have no idea about the performance of solar, but if it generally keeps up then seems to us cold start would be the way to go. But if it needs a lot of help, using a boiler aquastat would cut down on delay for hot water.

EBEBRATT-Ed

@New England SteamWorks

normally with an indirect the boiler is cold start and you maintain temp in the tank, not the boiler

hot_rod

You could set the switch over temperature, solar to boiler, to 110- 120°F, so it give you some DHW while the boiler and tank crank up.