Trying to understand my complicated boiler system

ABQBrodie

This system was installed a few years ago and its been working OK, I think it could be better. The guy that installed it got pissed off at the general contractor and won’t communicate with me anymore. Can’t seem to get the radiant floor heat to work consistently. Not sure what to do with the valve connecting the radiant floor HOT/COLD. Not sure what to set the temps on the IBC SL 45-260 Boiler to, it seems to cycle on and off a lot. The Indirect water heater has a Honeywell thermostat connected to the boiler, should that be a temp sensor only. Let me know what you think and how it can be improved. Thanks.

hot_rod

Not sure what the valve next to the 3 way mixing valve is partially closed. It should regulate with full flow to both H&C ports.

It's a 3 Cv valve and they often get undersized. Do you have the design for the radiant zone? It also needs the HOT port getting water at a temperature 20° warmer than the mix temperature it is set for. It blends hot with cold return to achieve mix.

Most of the new mod cons have functions built into the control to help minimize short cycles.
Ramp Delay for examples holds the boiler at it's lowest firing rate for selectable periods of time ramps up in small steps.
Anti Cycling prevents the boiler from firing after it shuts down for a selectable period of time.
Outdoor Reset adjust and lowers water temperature to also help short cycles.
You need to sometimes massage all these settings to optimize the boiler.
They include these features for exactly your application

Grab the manual and read up. Most boilers have You Tube videos explaining control settings, or try their website.

unclejohn

The Wilo circulators or for that matter any circ. is not supposed to be installed with motor up. Not sure if that will help but there is a possibility of over heating and shutting down.

hot_rod

So it looks like a dual coil indirect, solar feeds the bottom, heat for radiant off the top. The piping for that is a bit odd. Call it P3 pulls from the primary loop and goes to the upper coil, intended to feed radiant from the boiler, probably when solar (upper coil) is depleted? That tank does need to be maintained by the boiler on non solar days for DHW.

I'd like to see that piped a bit different where there is a separation between the two, hydraulically speaking. It's a workable concept, but the throttled valve tells me it is not working as intended.

If that is an I-Solar plus control it has the ability with two relays to help out there. I think another primary secondary piping at that point would solve the radiant which has two competing, or series circs now.
Circulators should be horizontal as @unclejohn mentioned.
I don't like swing checks in hydronics, the one by the B&G may rattle?

This is a workable design, needs a few tweaks.

Where is this job? Colorado by chance?

ABQBrodie

Swing checks = Check Valve? The B&G is the big red pump? What check valve do you recommend? Thanks for the advise on the pump installation, I’ll fix that. I don’t understand the piping from the primary loop to the Boiler return, shouldn’t that be going in the other direction?

ABQBrodie

Albuquerque

hot_rod

First things first, how many collectors do you have. Unless you have 6 or more it's really not going to provide a lot of heat contribution. Sometimes the cost and complexity to chase the solar out of a cold winter sky just doesn't pencil out.

That's the solar thermal Catch 22, you get the most when you need it the least, and vice versa.

Since you have all the right stuff, it may be worth your while to chase it? Depends on what you have to pay to tweak that system.

In your area it is certainly worth chasing the DHW, you have a good setup for that. You might just separate the two systems, solar should contribute 60% or more to your DHW load.

Here is one method for toggling between the solar and boiler for the radiant.
That solar control, I think, has two 120V outputs. The second output wires to a 120V 3 way zone valve. When the tank has energy to give it feed directly to the radiant. If not it switches position to the boiler.
Here is a schematic, not exactly what you have, it doesn't show the high temperature loads off the boiler loop. But it explains the solar interface and how to wire it.

Is this something you want to tackle? You need both some piping modifications, and configuring the solar controller to match. Or do you want some solar contractor connections? There are a handful in your neck of the woods.

Ironman

@hot_rod,
Bob, I think this is the piping concept that’s being used for the radiant floor. Using the heat stored in the dual coil indirect to power the small radiant zone. Ignore the piping to the left of the boiler in the drawing.

Ironman

It looks like the actual piping is not quite the same as the drawing concerning the radiant mixing valve and pumps.

hot_rod

Ironman said:

It looks like the actual piping is not quite the same as the drawing concerning the radiant mixing valve and pumps.

There is a circ feeding off the P/S to the upper coil and radiant mixer. Then a circ on the mix outlet of the 3 way. And a valve choked down about 80%. Looks like an attempt to try and balance away too much pumping? Needs to be a hydraulic separation in that piping.
Or the 3 way zone valve choosing one or another piping path.

Yeah, there are a number of way to improve this, trying to figure the best path based on what the actual goal is.

ABQBrodie

Not to concerned about the solar. I really need the radiant flooring to work consistently. Shouldn’t the radiant floor and Boiler circuits be tapped off the primary loop similar to the way the radiators and spa heat are.

hot_rod

Here is how a 3 way valve ties into a primary loop.

It just needs a single circulator on the MIX port of the valve.
In your system you have two circulators in that mixing valve loop or connection.
And the reason is they are trying to involve the upper solar coil in the mix, it will not work properly, which is why you see that one valve closed way down on the 3 way valve.

If you pipe it like this and the valve is sized for the actual load, and working properly, it's that simple.
I doubt you can fight you way out of the problem with the piping as it is. Looks like someone has tried