Is My Solar Heater / Gas Heater Plumbing Okay?

[CoolInDaPool]

Hi folks,

I have a new build and the initial system startup was just completed last week. Our system has both a gas heater and a solar panel heating array installed--the gas heater is plumbed directly off our filter and the solar heater follows the gas heater. My concern arises from the sequencing of the gas heater and solar array, which contradicts every diagram I have ever seen. Does the gas heater / solar heater plumbing sequencing matter?

This simple diagram shows the plumbing configuration of our equipment (blue lines = cold water. red lines = hot water):



From the pool/spa the plumbing goes through the pump to my filter and directly into my gas heater. After the gas heater, there are a series of auto valves that either flow directly back to the pool / spa or can divert water up through the solar panel array before returning to the pool/spa.








What concerns me is every diagram I have been able to find shows the solar heater array in line prior to the gas heater (example below). This sequencing seems more logical to me, but what do I know? So I'm coming to the experts...help!



Do I have an issue here? Or is the current configuration of my system acceptable?

Thanks in advance!

 

[cowboycasey]

The only thing I would change would be to add a heater bypass.. That would give you the ability to bypass the largest flow restriction in your setup.. You already have a solar bypass..

As for the setup where the solar goes into the heater that is used when the solar does not heat the water enough, then you could also use the heater to heat the water more..

Heater Bypass - Further Reading

www.troublefreepool.com

 

[setsailsoon]

My installation was as shown in your second diagram where flow to the solar panels splits off after the filter and before the gas heater but I think adding a gas heater bypass as @cowboycasey suggests is a better option. My Intellicenter would automatically switch to gas heat when there wasn't sufficient heat available from solar. This would allow me to heat the pool to a desired temperature in the afternoon before our evening swim even when there were sporadic rain showers that we often get in Florida. If you add an actuator on the gas heater bypass valve you could set it up such that the bypass valve opens when the gas heater isn't in operation.

Chris

 

[ajw22]

Yes, gas heater / solar heater plumbing sequencing matters.

You will not have proper temperature control of the water for the system to decide when to run the gas heater. You want the gas heater to run only when the solar cannot hold the water temperature set point. So you need to give the solar first priority in heating the water in the loop. Then the gas heater can add any remaining heat needed to get the water up to temperature.

The way you are setup the gas heater will see cold water and run first and heat the water and the, solar system will see warm water and think it does not need to heat the water further through the panels.

And also install a Heater Bypass - Further Reading while they are fixing your plumbing.

 

[CoolInDaPool]

Thank you all for the quick replies. I suspected things were plumbed incorrectly for all the reasons you highlighted--especially with the prioritization of Solar over Gas heating. Question: Can any of this be managed with the Automation logic if the Solar is properly configured and 'prioritized' over the gas heater? It's frustrating that the Sub who installed the physical equipment and plumbed it sequenced it this way. Even more frustrating that the PB had the piping laid out this way coming into the Equipment Pad to begin with which led to the "Equipment Sub" to take the lazy-man route.

As this is literally all brand new and I haven't finished paying my PB, should the PB / "Equipment Sub" be fixing this plumbing? The correct setup really feels like "Pool Plumbing 101". I will also bring up the "Heater Bypass" piping with actuating valve -- seems obvious and there is loads of space prior to the gas heater to install it.

The PB supposedly has 30+ years of experience and the Equipment "Sub" has 18 years experience...but it has often felt like this is the first pool they've built or serviced. Everything has been piecemeal and poor craftsmanship requiring loads of rework. I'm sure their crews don't have that same 30+ years experience. Unfortunately, very little of what has been done on this project seems to be 'by the books' based on what I've read on the web and TFP (I'm working on a "New Pool Build" post...but it is a monster).

 

[ajw22]

The only thing the automation knows to control the solar and gas heater is the water temperature. Where are the temperature probes placed for the water temperature and solar temperature? I doubt they are in a place where the solar can operate properly without getting confused when the gas heat is on.

Your builder should replumb and fix the heater sequence. There are loads of documents showing the solar before the gas heater. Let him show you any manufacture who recommends it the way he did it.

Contractors doing individual tasks often lose sight of the big picture in how equipment needs to operate together. Individually they are installed correctly. Together they are installed incorrectly. Basic lack of oversight by the GC/PM.

 

[setsailsoon]

I've never messed with Hayward automation but with my Intellicenter automation had a solar panel temperature input and actual water temp. I could set it to maximize solar so that I got maximum benefit when it was sunny. If clouds decreased solar heat temp difference to a certain level it would switch to gas heat. This delta T was adjustable. When it selected solar I also increased the pump speed so it would provide additional head to get to the roof. It was actually fun to watch this happen.. I could see the switching and the temp profiles. My wife would just shake her head when I told her I wanted to watch the valves turn! I could also select solar only or gas heat only. Hopefully your Hayward can do something similar. My iAqualink only had the ability to control solar.

There are a lot of great builders that know nothing about automation unless it's the one system they've been using for years. It's just like their understanding of salt pools. Doesn't necessarily mean they are not good builders just they are behind in the latest innovations. Sadly, many are.

Chris

 

[MSchutzer]

You really want to have the gas heater after the solar system for all the reasons listed above, but primarily to reduce the flow restriction that the heater causes. For the solar system you need typically need to push the water up to the top of the rooftop and that creates a lot of extra head for the system. Even when plumbed in the right order you will have to run your pump at a faster speed to overcome the head loss and assure that you close your solar system’s vacuum relief valve. If you have an additional flow restriction due to the heater you’re going to have to run the pump even faster to get the pressure you need at the top of your panels.

You really do want to fix that plumbing error otherwise it will be costing you extra power for the life of the system.

 

[CoolInDaPool]

You really do want to fix that plumbing error otherwise it will be costing you extra power for the life of the system.

What kind of additional power cost are we talking about?

I've asked about rectifying the plumbing, but my PB is playing the absentee game, so I've been futzing around with what I have for the time being. I've noticed the pump is working hard almost all day and never quite gets down to the lower rpm levels -- even after temp is reached with solar and the valves bypass the solar heater it doesn't seem to drop to 1,640 rpm. I've got a schedule set at 5 hours at about 70% (2,450 rpm) and 5 hours at 45% (1,640 rpm) or so. The Solar Heater has a minimum pump rate of 80% (2,760 rpm). Been paying attention to the wattage output and there is a considerable difference in power consumption between the 2,640 and 2,760 rpm settings. I cannot tell if this is happening because of the plumbing or not... but I want to figure out a more efficient power / pump scheme.