Proper Filtering of Spill Over spa

[TFP-Guy]

Hey again,

I have an indoor pool which has a "spill-over" spa attached to the pool in such a way that the top little bit of water in the spa will spill over into the pool. The pool and the spa run off of the same filter, pump circulation, and heater. I have valves that control water from the pool and/or spa that goes to the heater and then another set of valves which controls water to the pool and/or spa from the heater. Currently, I have it set to 30/70 to and from the pool/spa respectively. With it this way, the spa runs about 1 or 2 degrees hotter than the rest of the pool (27 C / 80ish F).

Eventually, I will want to get the hot tub at proper hot tub temps (38 C). The only way I think I can do this without heating up the pool would be to divert all of the water from the pool to the heater, and then all the water from the heater to the spa. The spa would constantly spill over the hotter water into the pool, and the pool would heat up by the residual water that way.

My concern, though, is that the water in the pool wouldn't have any of the returns flowing water in. How would that affect the pool sanitation, filtering, and general flow of water? The only source of water the pool would receive would be the little bit that constantly spills over into it from the spa, and that doesn't come in with any force.

 

[ajw22]

Do you have automation on your valves or change them manually?

Your pool/spa combo is designed so that in POOL mode you circulate water to the pool and spa as you describe. When you want to use the spa you or your automation turns the valve so all return flow goes to the spa and suction comes from the spa. Then your heater should be able to rapidly heat the spa water to the desired temperature.

When you are done using the spa you switch the valves back to POOL mode.

Post pics of your equipment and valves.

 

[TFP-Guy]

They are manual valves, I can definitely get you some photos when I get home tonight.

What you're saying makes sense. I suppose it will have to be an on-demand system where the hot tub is heated when needed only. This does have the benefit of being much more cost effective in that I'm not heating up a hot tub that's hardly used. I imagine that by keeping the spa at the same temperature of the pool (roughly 27 C), it wouldn't take too long to get it up to 40 C? It is a somewhat small spa, I'd say a 2 person spa most likely.

The heater (a heat exchanger) does a pretty good job. It is able to get my 6800 gal pool up 5 degrees C in under 10 hours (ie; overnight).

 

[ajw22]

You will learn how long before you plan to use the spa you need to turn the valves and turn on the heater.

 

[TFP-Guy]

Here are the photos (one showing all the pipes) and the other two showing close-up shots of the two valves.



As you can see, I have it set 70/30 towards the pool/spa right now as I want to make sure the pool water is getting filtered/circulated the most right now. I suppose when I want to heat up the hot tub, I'll put both 100% towards the spa and see what happens!

 

[ajw22]

Here are the photos (one showing all the pipes) and the other two showing close-up shots of the two valves.

View attachment 106378 View attachment 106377 View attachment 106376

As you can see, I have it set 70/30 towards the pool/spa right now as I want to make sure the pool water is getting filtered/circulated the most right now. I suppose when I want to heat up the hot tub, I'll put both 100% towards the spa and see what happens!

That is the best plan.

An observation... you can have from pool be 100% (close from spa) and have the TO valve be 70/30. The spillover will send the water from your spa to the pool. It will improve your pool circulation.

 

[TFP-Guy]

I was thinking that too, but I suppose it'll require more energy as cold water will constantly be heated up. Whereas the other method will only require minimal energy to top up the heat.

 

[ajw22]

I was suggesting you normally run your pool that way. Not that you set that when you want to use your heated spa.

 

[TFP-Guy]

Oh excellent, I like that idea.

I haven't had a chance to test it yet, but I suspect that heating the spa from 85 to 100 shouldn't take much longer than a few hours. So I can heat the hot tub on demand and not have to worry about wasting energy for the rest of the hours/days.

 

[Richard320]

I leave mine set to draw only from the pool and return about 20% to the spa. With the heat on, the spa does get warmer than the pool just because it is less than 20% of the volume. If I really want the spa hot, I just set to 100% spa in spa out. It'll take it over 100 in a matter of minutes. When I'm done, turn things back the way they were and let it flush the spa into the pool.

I noticed that kids like the spa because it's shallower an warmer. When they refused to get out when Mom said to, it was easy enough to reverse the flow and kill the heat and chill 'em out!

I used to try drawing from both the spa and pool and balancing the flow so just a little spilled over. Too scary. As the filter loads up and the flow slows, the shorter run (for me) from spa to pump means the spa gets drawn down faster than it gets returned. Lucky for me that I spotted it before it sucked the spa dry and lost prime!

 

[TFP-Guy]

Thanks for your response!

My spa runs about 1C hotter than the pool (29C Spa | 28C Pool). To get it up to 100F like recommended (or 37C) shouldn't take too long. I have my first guests over at our new place for a little swim tomorrow so I'll turn up the thermostat during the day and reverse the valves and see what comes of it!

I think we've dealt with many of the same issues, but it's good to see I'm not alone. I too, tried to balance the spa and pool valves so that the spa was full but not overflowing (this was before I knew this was by design). It created several situations where the spa water level dropped suddenly and I had to quickly reverse my changes to get it back up. In the end, I found a 70/30 split between the pool and spa (for both valves) to work well to keep the pool returns circulating a decent amount of water and the spa not overflowing at a big rate. For me, my spa is furthest from the pumps, but still it's tough to get it balanced correctly, so I've documented where to keep the valves during normal usage. So far, the spa hasn't been used at all (I'm not a big spa user, and my wife is pregnant), but I anticipate others will want to use it once the weather gets cooler in a few months.

I noticed that kids like the spa because it's shallower an warmer. When they refused to get out when Mom said to, it was easy enough to reverse the flow and kill the heat and chill 'em out!

Hahaha, I like the way you think! I will definitely keep that trick handy should I need it. Adults too!