1 inch thermopex, plate exchanger and pump

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Keyser4

Member
Oct 1, 2014
2
EUP
Well I probably should have done a little more homework but already purchased and installed 1 inch thermopex from Central Boiler dealer. I have about 254 feet total loop. I realize the pipe only has an I.D. of 3/4 inch. I purchased a Heatmaster 4400 used only 5 years for $2K and that will be the outdoor wood burner. I have a Lokinvar propane boiler rated at 150,000 btu in basement with zoned pumps to my infloor radiant heat plus a boiler mate for DHW. My house is super tight ICF rated at R50 equivalent walls and R60 in ceiling but my heat loss is way too large of windows and lots of them that the wife picked out. I have been averaging $3K in LP use because we are in the far north on Lake Superior in the UP of MI. and have around 4000 sf heated with basement and have 6 people living in the home. My wife 4 daughters and myself so lots of hot water use. So I will be installing a 50 plate heat exchanger to isolate the open loop from my closed loop system. I was advised to install a really good hot water filter on the open loop prior to the heat exchanger to prevent any crud from plugging up the plate exchanger. I found a strainer with a magnetic core that will filter out any particles and also trap any ferrous particulate. It is rated at 13gpm so this is where I may have screwed myself already as the 1 inch thermopex is in the ground and the stove is set. I am thinking of installing Webstone full port valves on the open loop side of the plate exchanger so I can back flush it as needed. or even pump vinegar or cleaning solution through it as needed. I have really good well water but was told the efficiency of the plate will go down as scale builds up over the years and with regular back flushing you can restore it somewhat. The wood master came with a Taco pump and was located about the same distance from the home from the guy I bought it from. He hooked up to Natural Gas so that is why he didn't need it anymore. He had water to air heat exchanger and 1 inch pex in foil bubble wrap. So I don't know if my plate exchanger, and the filter fittings would be too much restrictions or I will be fine. Any advice is greatly appreciated as I haven't purchase the hot water filter but I like that is has a strainer and the magnetic core that you can clean. I have read that it is way better than just a wye strainer. The filter is called BoilerMag. I also looked at the Rusco spin down sediment trapper filter/strainer which is rated at 20 gpm. Thanks in advance.
 
Yes your 1" will be a restriction in how much heat you can get moved from the OWB to the house. Whether it will restrict too much so you can't stay warm, might come down to running it & seeing how it does, at this point. Aside from poorly insulated underground piping (the Thermopex is good, wrapped is bad), undersizing is likely the second most common shortcoming in systems that don't do well.

I would use a bigger HX than 50 plate. I would go at least an 80. That might help overall.

Good plan to plumb in those valves for easy flushing. Some go years without it, some have issues after a few months - all comes down to water quality. I don't have any experience with the filtering stuff, hopefully someone else will chime in. But you should likely also investigate boiler treatment, to help avoid corrosion related issues arising.
 
That's a very good filter and anything is better than nothing. I just have Y strainers on my heating side and a whole house filter and softener on the DHW side to protect my flat plate exchangers. I've cleaned them a couple times this season and there's plenty of crud in the strainers and filter every time. Definitely run boiler treatment in the OWB and I'd also recommend it in the pressurized system. I also agree with Maple1 in that a larger plate exchanger can help overcome undersized lines.
 
I'm on my 6th winter with a Garn 1000 - I have a 50 plate HX I set up with a Y strainer when new. The performance has gone down over the years, even with keeping the strainer clean, trying to clean the HX several times. A month ago [i know, what took so long?] I finally cut out the strainer & installed a cartridge filter from Garn in it's place. As soon as the weather gets a little better, the HX and I are making a trip to a radiator shop for a good flush job. The below 0 days we had, if not for the woodstove I put in the basement, I might well be single now................ The filter from Garn is for up to 250 degree water, or some such temp, under a hundred bucks with 4 elements.
 
If you plumb in tees with boiler drains and and ball valves to isolate you can flush with CLR, Lime Away, etc with a small utility pump and hoses.
Is your radiant in a slab, suspended or with plates?
If it's lower temp radiant the low-ish flow rates from the OWB won't be an issue. The delta t might have to be larger than "normal" on the main loop though.
 
If you plumb in tees with boiler drains and and ball valves to isolate you can flush with CLR, Lime Away, etc with a small utility pump and hoses.
Is your radiant in a slab, suspended or with plates?
If it's lower temp radiant the low-ish flow rates from the OWB won't be an issue. The delta t might have to be larger than "normal" on the main loop though.
yes all radiant infloor is in concrete on subfloors, I have decided to use webstone full port valves at least on the open loop side, not sure if I should do the same on the closed loop too?
 
I don't recall ever seeing the pressurized boiler side of a flat plate clog but it wouldn't hurt to make it easy to flush.