Water to Water HP OK at 120 LWT for long period?
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coldNHUser is Offline
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27 Feb 2015 10:21 AM
I am looking to change my radiant heat from fossil fuel to Geo. I have reviewed several water to water heat pumps. They show leaving water temps into the 130s. My question is, I may have a month or so where we need about 120 deg water pretty much constantly. Can these newer HPs provide almost constant 120 deg water, or is that putting too much strain on them? Secondly, I've seen from the forum the advice on installer being more important than brand. That being said, are there brands more know for reliability of water to water units, some to probably avoid? We are in souther NH as far as climate goes


joe.amiUser is Offline
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27 Feb 2015 10:58 AM
Insstaller does matter most particularly with WTW.
One can provide 120F or higher somewhat reliably, but better to bring down the requirement if possible instead as 120F only gives you about 2 COP when something in the 90's might be mid 3's.
Radiant panels, baseboards, hydronic fan coils etc. all offer ways to add btus without cranking temp- up.
j


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27 Feb 2015 01:09 PM
120 is the worst case, but this winter we had long stretches of worst case sub zero weather. Much of the winter, wouldn't need that warm. I am planning to add some low temp baseboard (smith environmental) as well so temps may come down a little. Any brands or models stand out in the Water to Water heat pumps?


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01 Mar 2015 09:51 AM
The big three are Bosch, Climatemaster and Waterfurnace. If you focus most on who you buy it from (versus) brand, everything else will take care of itself. Pay particular attention to those dealers with geo-hydronic experience. Watch for buzz words (i.e. outdoor reset, buffer tank) as well as someone who pays attention to pumping strategy.


Joe Hardin
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We Dig Comfort!
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coldNHUser is Offline
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01 Mar 2015 11:18 AM
Thanks Joe,
I understand outdoor reset and the need for a buffer tank, what pumping strategy are you thinking about? Variable speed buffer tank to the floor?

Anybody using water to water HPs to radiant floor and low temp baseboard? Any advice - How reliable has your HP been at being the sole source of heating water all season? My floor is a staple up large diameter pex on 16" centers with light aluminum transfer plates, works pretty well but needs 90 - 120 deg water depending on OAT. I have also installed a small section of Smith Enviromental low temp baseboard which adds significant heat from say 105 - 120 deg. I plan to add more and may be able to bring down my top water temp by having more total emitter area. http://smithsenvironmental.com/html/he.html

glad to hear your experience...



coldNHUser is Offline
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10 Mar 2015 09:29 AM
just checking back to see if anyone with a water to water heat pump can tell me what the max temp you are using is. Any problems trying to get water at 115 or 120 deg.


Palace GeothermalUser is Offline
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10 Mar 2015 10:03 AM
Hi,


you have a better chance of getting discussions if you go here: https://www.geoexchange.org/forum/


Dewayne Dean

<br>www.PalaceGeothermal.com<br>Why settle for 90% when you can have 400%<br>We heat and cool with dirt!<br>visit- http://welserver.com/WEL0114/- to see my system
coldNHUser is Offline
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10 Mar 2015 10:14 AM
great, thanks Dewayne I will try it.


switchgrassfarmerUser is Offline
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15 Mar 2015 11:41 AM
coldNH, hoping you got responses in the other forum.

FYI, we do make 120 degree LWT with our 3 ton water-water geo system. I have attached ten days of data from this past very cold February as collected from a sensor on the input to the buffer tank. (We had a number of below zero nights reaching -13 one morning, our design temp is +7 degrees.) Times where no hot water was made were days where the home was heated with passive solar gain, our masonry heater, or both.

120 degree LWT really draws down the temps from the well, and when that happens the run time on the geo unit becomes quite long. Fortunately our well, big enough for a 5 ton system, recovers and was hovering at about 40 to 45 degrees in early March.

Net-net, it's all about having an adequate well, or alternate heat sources, or both.


Attachment: GeoCompOut.pdf

switchgrassfarmerUser is Offline
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15 Mar 2015 11:51 AM
BTW, I should have noted that our temporary USB thermocouple lash-up didn't perfectly capture the LWT temps. Readings as measured by the Tekmar controller's probe in the buffer tank are actually a number of degrees higher. Just didn't have any way to easily capture that data.


coldNHUser is Offline
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15 Mar 2015 11:52 AM
Thanks sgf,
I did some searching in the other forum and haven't gotten any further yet, there seems to be a lot of raw material there to go through. Glad to hear 120 deg is working for you. That seems to be my worst case, as I said earlier, I am looking at adding additional heat emitters to possibly bring that down a little too. How long has your system been running and what brand/model if I can ask? thanks for responding!


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15 Mar 2015 12:29 PM
Posted By coldNH on 15 Mar 2015 11:52 AM
How long has your system been running and what brand/model if I can ask?

We have a ClimateMaster Tranquility TMW 036. This is our first full winter in operation. (Initial start up in an ice cold house January 2014.)


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15 Mar 2015 12:37 PM
thanks, CM is well supported here so that unit is on my list too, great.


docjenserUser is Offline
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22 Mar 2015 08:23 PM
Climatemaster is maxing out around 127-128 F degress F Leaving Load Temperature (LLT), Hydron has a bulletin out saying they do not want the LLT above 125F, Waterfurnace is running well at 135F LLT.


www.buffalogeothermalheating.com
coldNHUser is Offline
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22 Mar 2015 08:36 PM
Thanks, docjenser, it sounds like you are happy with the Waterfurnace water to water for these "mid temp" hydronic applications. Has your experience with the waterfurnace units been very good overall? The smith environmental low temp baseboard I installed as a test puts out a lot more heat at 120 deg vs. 110 so it would be good to be able to deliver 120 deg water to it in the coldest weather.


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22 Mar 2015 10:14 PM
Make sure you actually imply a piping design so your water temperature is not mixed down in the buffer tank, so you deliver actually 120 F to the baseboards. Also you should incorporate and outdoor reset so you don't run it at 120F when you don't need it. Here is an example. http://welserver.com/WEL0384/


www.buffalogeothermalheating.com
coldNHUser is Offline
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23 Mar 2015 09:25 AM
I see your example. I want the heat pump output to be able to go directly to the load when the heat pump is running and the load is calling. You are doing that nicely, right now you're sending 122 deg water from HP to floor and fan coils. It looks like the heat pump lw can go to any zone but when all zones are closed it is simply forced through the buffer tank as the last resort. That sounds pretty effective - any tricks to that? I do control systems for work so I would be able to do any valve logic, OA reset, etc.


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24 Mar 2015 11:51 PM
No tricks needed. Just the pump between the tank and the zones must be a constant pressure variable speed pump.

WF just introduced high temperature 3-5 tons w-w water high temp heat pumps, 150F capable http://www.waterfurnace.com/products.aspx?prd=504W11


www.buffalogeothermalheating.com
coldNHUser is Offline
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25 Mar 2015 08:47 AM
Does the zone pump run whenever at least one zone is calling, and the lower pump run whenever the HP is running? I see that would force all water through the buffer tank only when no zones calling. Very nice. Is the well diagram simplified as far as the HP water loop and the load loop as they enter and leave the buffer tank?

I saw the 7 ton water furnace, didn't know they had a 5 ton high temp. Have you been able to try any of the high temp ones out yet?


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26 Mar 2015 12:21 AM
They introduced the vapor re-injection high temp HPs this weekend, 3-5 tons. We put about (10) high temp 7 tons in so far. They work sweet. Impressive design.
yes, the variable speed is running when at least one zone is calling, and the constant speed runs whenever the HP is running.

PM, and I can send you a more detailed rendering.


www.buffalogeothermalheating.com
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