Trying to heat pool w/ EKO40

[jbush]

After installing a pool heat exchanger to heat my pool with my EKO40, I have been struggling to see a difference in my pool temperature. I purchased a 250K btu heat exchanger to heat my 20,000 gal pool per the sizing chart. When the boiler is up to temperature, the pipes from the boiler are hot entering the heat exchanger and they are cool leaving, however I can not feel any heat in my water pumping into the pool. I have run the boiler 8-10 hrs a day and can not raise the temperature of my pool. Is there is anybody successfully heating their pool with a wood boiler? If so, what kind of results are you seeing & what is the key to your success?

 

[benjamin]

I'll throw out some guesses...

20,000 gallons works out to 160,000 lbs of water so if you're getting 100,000 btu per hour out of the boiler, 8 hours should raise the temp of the pool 5 degrees, so you should notice some results.

My guess it the boiler loop to the heat exchanger is not circulating enough flow. Does the boiler idle during the time it's running? If the boiler is producing the heat, it should be fairly simple to figure out where it's going.

How hot is the water in the pool and how long have you been heating it? I know last night was much cooler and drier than it has been for a while, which would cause a huge heat loss in a warm pool.

 

[heaterman]

What are the supply/return temps on the EKO?

What size circ do you have on the boiler side of the pool HX?

 

[goosegunner]

Mine has been working this summer. Taylor 450 with a 360K btu exchanger.

Talked the whole situation over with Heaterman earlier this summer. My water is warm returning to the pool but I have a 50 degree delta T. Not getting enough flow on the 140' of 1" pex.

I need to have a good coal bed and keep an eye on the water temps. I can get by for now but I will be upgrading my lines to a bigger size to reduce the Delta T and Maybe buying a bigger boiler. It is an experiment in progress.

If I had a Gasser right now I would have problems because my supply will be 170 and the return will be 120 degrees. It is all related to the Boiler line gpm flow I am getting.

gg

 

[goosegunner]

After installing a pool heat exchanger to heat my pool with my EKO40, I have been struggling to see a difference in my pool temperature. I purchased a 250K btu heat exchanger to heat my 20,000 gal pool per the sizing chart. When the boiler is up to temperature, the pipes from the boiler are hot entering the heat exchanger and they are cool leaving, however I can not feel any heat in my water pumping into the pool. I have run the boiler 8-10 hrs a day and can not raise the temperature of my pool. Is there is anybody successfully heating their pool with a wood boiler? If so, what kind of results are you seeing & what is the key to your success?

I do have a home made solar set up that helps but I can get close to 1 degree an hour if I have the large coal bed and keep an eye on it. Last week of May I had the pool at 90 degrees until my wife told me to turn it off, its too warm.

My pool is also smaller at 15,000 gallons and has the aid of solar.

gg

 

[jbush]

Thanks for the replies. I suspected my problem is water flow and judging by the replies, that appears to be my issue. It is 90' from my boiler to the heat exchanger, so I have a total of 180' flowing thru 1" pex. I just have my Taco circ pump at the boiler. Today I increased the pressure of my system to 22 PSI. Last winter was my first season with this boiler and I was heating the house with 11-13 PSI (I have baseboard heat with 2 zone pumps). Will the increased PSI help? What other options do I have for increasing water flow from my boiler? I do not know temp of my return line. I guess I should find out.
Thanks again for the help.

 

[goosegunner]

Thanks for the replies. I suspected my problem is water flow and judging by the replies, that appears to be my issue. It is 90' from my boiler to the heat exchanger, so I have a total of 180' flowing thru 1" pex. I just have my Taco circ pump at the boiler. Today I increased the pressure of my system to 22 PSI. Last winter was my first season with this boiler and I was heating the house with 11-13 PSI (I have baseboard heat with 2 zone pumps). Will the increased PSI help? What other options do I have for increasing water flow from my boiler? I do not know temp of my return line. I guess I should find out.
Thanks again for the help.

I do not personally own a gasser, From what I understand it needs return protection if the water temp is too low.

Could it possibly be activating the return protection to save your boiler?

Would that not then provide even less hot water going to the heat exchanger because it is trying to protect the boiler?

My runs to my primary manifold are 140' each way. I then have a secondary pump that sends it 43' to the pool exchanger and back to primary.

If I had a gasser right now it would not work. The return temp would be to low. My taylor has 340 gallons of water so It will run for about 45 minutes then I need to watch it closely and make sure the fire is raging.

I would install some temp gauges at the heat exchanger it will give you a better understanding of what is going on. Unless you can get more flow you, like me you would be better served with a smaller heat exchanger. People that sell these exchangers and encourage over sizing do not understand pex flow rates, btu ratings, or delta T. After using mine and seeing it first hand I am just beginning to understand it. There is a reason my boiler connections on the exchanger are 1-1/2".

Did you install bypass before the heat exchanger? If you did you could reduce pool flow through the exchanger to lower your Delta T. It would lower your heat transfer but if low return temps are causing your problem it might let you get by.

Good luck

gg

 

[jbush]

Goosegunner, your evaluation makes alot of sense. I definately see the value in knowing the return water temp, so I will install temp gauges as you suggested. I do have a bypass on my system. I wil try opening both flow valves to reduce the amount of water running thru the heat exchanger on the pool side? My boiler does struggle to reach the set temp, so I think you are on to something.

 

[goosegunner]

Goosegunner, your evaluation makes alot of sense. I definately see the value in knowing the return water temp, so I will install temp gauges as you suggested. I do have a bypass on my system. I wil try opening both flow valves to reduce the amount of water running thru the heat exchanger on the pool side? My boiler does struggle to reach the set temp, so I think you are on to something.

Do you have return protection at your boiler? Can you tell if it is in operation when you are heating the pool.

Also I see you have no storage. I know it is expensive to set up but It would give you a buffer.


gg

 

[jbush]

I have a mixing valve on my return side. I do have 20,000 gallons of in ground storage, the problem is I can't heat it! JK. I have considered storage, and may add it in the future. My system worked wonderfully for heating my house & DHW last winter, if I could only solve this problem with my pool I would be a happy camper. I will start by adding the temp gauges, but I fear it will only confirm what I suspect to be true, that I am not getting enough water flow to effectively transfer heat. Then the question becomes do I install a second circ pump or reduce the size of my heat exchanger?

 

[SolarAndWood]

Do you guys have insulated pools? Between the evaporation loss and the 50 degree ground temps, you are going to be processing a lot of firewood. Just curious, I knocked my small inground in two winters ago because 60 days of swimming wasn't worth the drainage issues it created. If I could keep 10K gallons above 83 for 4 mos, it might be worth it.

 

[heaterman]

Ya know Ashless........before you tear up lines, change circs and heat exchangers and consider different controls, you should realize that an EKO 40 may not have enough horsepower to heat that pool. If I recall correctly, a 40 is around 120 Kbtu output and that's not a lot of capacity when it comes to heating/maintaining a pool.

 

[benjamin]

I think the horsepower is there to heat this pool. I don't own a manufactured gassifier, or a pool, but I've seen enough pool heaters in operation, and the bills they generate, to know that it is doable. We're not talking about trying to heat it up in early May or keeping it warm into October, it's hot and humid out, which both dramatically reduce the heat loss of a pool.

If the boiler isn't idling during an 8 hour burn, and it's heat exchangers aren't hopelessly insulated with soot, then it's making a lot of heat over that time that has to be going somewhere.

Because the boiler side of the heat exchanger has hot in and cool out, I suspect there isn't significant flow, but then the boiler should be idling, or overheating, unless it's possible that the boiler sooted up that much (I don't know if that is possible or not).

Or maybe the pool is leaking constantly and being refilled with cold well water? What was the temp at the start of the heating attempt and when was that?

 

[jbush]

My pool water temp has been ranging between 80 - 84 degrees. Which is perfect for swimming, so I am not complaining. But this has been a hot summer so the water would warm naturally. No matter how long I burn for I have not been able to achieve a temperature warmer than 84. I cover my pool with a solar blanket at night, so this morning for example the pool was 80 degrees when I pulled the cover, after burning all day it only went up to 82. Was this warm up from the sun & air temp or from my boiler? The boiler is operating properly and I am sure I do not have a leak. I did notice a difference today when I opened my bypass valve to divert some of the pool water. My boiler maintained its temperature & idled more so I do think I have an issue with water flow and return water temps. This is my first season so I did not know what to expect. Perhaps I need to adjust my expectations.

 

[benjamin]

I'd guess that the two degree rise in one day is mostly boiler, but that's not as much as it should be.

You mentioned the bypass (pool pump bypassing the heat exchanger?) making the boiler idle more. With that large of a heat exchanger, and adequate flow on the pool side, I don't think the boiler should idle at all, even if you keep it mostly full. If the boiler is idling then there is a block to the heat flow somewhere (boiler side of the hx most likely), if it's not idling but you're letting it burn down all the way between loadings then you're not getting full capacity and the two degrees per day is probably about right.

 

[flyingcow]

Good thread. I am planning on hooking up a hx from my boiler soon. I am using a propane fired unit right now. I can't find my paperwork, but i think my propane unit is rated for 150,000btu's? This will raise my(18x36 inground) 29,000 gal pool 1.5 degrees an hour, in a cloudy 70 degree day. If it's 75+ with the suns help it will do 2 degrees an hour. But we only use about 75 to 100 gals of propane a yr. We do not run heater all the time, just when we think it's going to be used. But you take a 65(or less) degree day it does struggle to heat up quickly and maintain. Seldom ever heat when this cold outside, too chilly to sit around the pool. But you can feel the heated water coming out of jets.

i figure with my 102,000 btu unit, I might get a 1 degree gain, but time will tell. We are in a good sunny location that does well to heat the pool naturally, use a heavy pool cover, etc. You mentioned a 2 degree gain in one day. My location/pool will do that every day the suns out on a warm summer day.

check out wwwbuilditsolar.com they have some simple looking DIY solar heaters that I should have had built and installed by now.

 

[in hot water]

If you know the flow rate thru the HX you can calculate the amount of energy being transfered. If it is plain water then Q= 500 X flowX Δ temperature

A 10 gpm flow (typical for a 100,000 BTU boiler) with 180 °F into the HX and 160 °F out would be

Q= 500X10X20 or 100,000 BTU/hr transfered

To determine the flow rate you could install a pressure gauge on both sides of the pump. Convert the pressure difference to feet of head, look up that on the pumps curve chart to see how many GPMs it is actually moving.

It sounds like the boiler side of the HX is transfering the load?

Is the pool fenced? Wind, even a small breeze really rips heat from a pool. Generally pool heaters are sized to the area of surface, not really the gallons of capacity. The load, both heat loss and heat gain, is a surface area game with pools.

There are a bunch of free pool heat sizing formulas on line DOE has one, so do the pool heater manufacturers.

I question that the boiler really can produce 100,000 BTU/hr without constant "tending"?

hr

 

[btuser]

I'm with in hot water. We need more math. For all we know the boiler/hx is doing its job and you don't have enough BTUs. My old pool heater was 400k natural gas. I've got a 20,000 in-ground pool with nothing but a solar cover this year and I'm maintaining 82-90 degrees in Southern NH.

What's your delta and flow on the pool side of the equation? Are you running the pool pump through the HX? Hard to compute with such a large flow.