OWB pump advice

[sstan]

Ok .. brain picking time .. dreaming of summer and using the OWB to heat my swimming pool. I picked up a HX and looks like I now will need a bigger pump. My current run is 100' (200 total including return) to the house exchanger .. the pool will be an additional 100' making it a 200' (400 counting return). My current pump is too small .. so I have been told to look for a taco 0013 or B&G;PL36 ... is there any other brand comparable that I should keep my eye out for? As everyone in these times I am looking for a deal!!

thanks,
Steve

 

[stee6043]

After just switching a Taco to a three speed Grundfos in my own system I must say I'm impressed with Grundfos. Having three speeds to choose from is great for tuning even if you may not think you really need it. All of this and the price of the three speed pump was less than the Taco 007 I was using previously. That's my two cents for you...

I'm sure all of the manufacturers have sizes that will meet your needs.

 

[jebatty]

400' of round trip run, what size pipe? How many gpm do you need to side A of the hx? What's the pressure drop in the hx at the desired gpm, side A. Same Q's side B. At the desired gpm and Side A input temp, what will be Side B output temp at desired gpm? Will you be getting the btuh you need to heat your pool at these specs?

 

[sstan]

Well I doubt I can ansewer all the questions... it is 1 inch insulated Pex. My design (in my head) is to put some "T" and valves into the lines just before my current HX .. divert the flow to the new pool one when needed ( by then it will be warm and I won't need the house HX). The new HX is one I one on ebay and EZZ-FLOW 130 .. 3/4 ports for the hot water and a 6 GPM flow desired. It actually is the HX for my 24 ft above ground pool per the companies specs.

 

[jebatty]

I'm not sure I'm understanding exactly what your plan is. FWIW, 1" - 400' - 6 gpm = about 13'-14' head. You have to add to this all other components (T, L's, valves, etc.) that add head. A Taco 0013 will deliver 6 gpm at about 29' head and about 23 gpm at 14' head, so it appears that, just a gut reaction, you probably are in the OK range for a Taco 0013 to get at least 6 gpm. I didn't look up the curves for the other pumps.

 

[DaveBP]

One more factor to consider in heating a pool is that the water returning from your pool HX may be a lot colder than water returning from any other type of load heating your house. This is great for one of the modern condensing gas boilers but can be a complication for a wood boiler.
It's vital to prevent condensation in the boiler by not allowing return water into the boiler below about 130F min. Seems like 140F is the temp controllers try not to go below.
Make sure you have a bulletproof method of return water temperature protection.

 

[sstan]

Thanks for the help guys .. sounds like your all confirming the Taco 0013 or the B&G;pl36 .. I was not sure of my evaluation of the pump curvers. I am concerned on the post concerning return water temp... Why is this a concern? I don't understand at all?

steve

 

[DaveBP]

I am concerned on the post concerning return water temp… Why is this a concern? I don’t understand at all?

If the water returning into the boiler is not above about 130F min. it can cause the water vapor in the exhaust to condense into liquid water along the inside of the boiler heat exchange surfaces. This will corrode the steel and reduce the lifespan of the boiler. This is true for most oil and gas boilers,too. The temperature of water returning from the house heating loads is often higher than this, especially if you are using baseboards. No big deal for some setups. Water coming back from heating cold water in a pool could be a lot colder than 130F.

I honestly don't know if it is a problem with your particular boiler. I've seen a lot of non-gassifier OWBs setup without return protection. Maybe they are immune or maybe such corrosion is considered normal.There are several pool and hot tub owners that post regularly here that could speak with a lot more authority than I.

Don't mean to raise unnecessary alarms.