hooking up hot tub temperature too high

[docgogo]

I need some help hooking up my new greenwood 200
At present i have 1"id pex al pex some people call it alumipex i have a maxflo mf 80 pool heater hooked up to hot tub when up to good operating temps with my 100 the hot tub will overheat and kick my high limit thermostat on the hot tub
Is there a way of tempering the water so it won't be so hot without replumbing the hot tub? thanks in advance

 

[cricco]

Yes. Use a mixing valve.

 

[Northwoodsman]

Not quite sure how your hooked up to your hot tub but here's how I am heating my 350 gallon jacuzzi with my EKO40:

1.) I removed the (2) heater wires that go from the relay on the hot tub to the 240V cartridge heater on my Jacuzzi (original OEM setup).

2.) In its place I wired a 240 volt coil relay and on the other side of the relay I wired my 24v zone valve.

3.) Thus, when the hot tub calls for heat it opens my Honeywell zone valve to heat the water via a shell and tub heat exchanger.
I am using my hot tub temperature controller just like I did when I had the 5.5KW heater hooked up to it.

4.) I leave my hot tub always on 104 F and it never gets below 103 F.

NWM

 

[BrownianHeatingTech]

If the issue is that the whole tub is getting too hot, then it's likely a control/wiring issue, in how you are operating that zone. We'd have to know how it's wired, in order to address it.

If there is a high-limit sensor in the piping, and that's what's tripping (ie, the heat exchanger is heating the water in the pipe too much, rather than the whole tub too much), then it's a flow issue in the piping. In that case, you either need to increase the flow on the hot tub side of the heat exchanger (or, look for any obstruction that might be artificially reducing it, like a part-closed valve), or decrease the flow on the boiler side. You can do that by using a smaller pump, if it's a pumped zone, or by introducing a restriction (a partially-closed ball valve, for example) if it's set up with a zone valve.

Joe

 

[2.beans]

its funny this topic came up. last night i hooked my tub up as described above and it confused the hot tub controller. i hooked the relay to one side of the heater element with a 120 volt relay though and the tub is wired 240. maybe thats my problem. it was giving a sensor imbalance code. the way i had it hooked up before with a seperate sensor the tub would over shoot even with a mixing valve. with out the hot tub pump running and feeding hot water into the tub from an external pump off from my boiler the water would stratify and not let the tub come on and mix the water up.

 

[rvtgr8]

I am grateful that this thread has appeared. I will soon be hooking up my hot tub and I am going to have to get this right. My wife wants 103*. Not 102* or 104*. The WAF on this is very high. I would rather bob for lobsters than screw this up. :ahhh:

Robert

 

[leaddog]

I have my tub hooked up like this,
My filter, ozonator pump runs full time into a hx and back to the tub.
I disconented my elect heater and conected one leg of the 220 to the pump that pumps the other side of the hx.
when I get a call for heat the hx pump comes on and when the temp is ok it shuts off. It operates just like the elect heater did but costs $30 a month less
leaddog

 

[2.beans]

with mine just hooking the relay to one leg makes the controller set all kinds of codes. i dont have that fancy of a tub im surprised it was smart enough to recognize this. im actually working on it right now just came up to get some tools.

 

[docgogo]

when i hooked my hot tub i put a maxiflo mf 80 pool heater with a zone valve with a ranco singel stage electronic temperature control
when the system calls for heat if my pipe temps are 145 or greater thats when i get the problem of kicking the hot tub into ohh mode overheat so i have to turn off the hot tub off turn down the temperature of the single stage control down run it for a few minutes then turn temp back up
If i knew where my first over limit thermostat was i could disconnect it this would help some

 

[2.beans]

i had been using a single stage ranco also, today im going to install the ranco sensor inline on the return side off the water going back to the wood boiler hx. this is close to where the factory sensors are located. i would like to have it hooked up like the other guys have for ease, but i cant come up with a good way to trick my hot tub controller. i do have mixing valve on the hx for the hot tub so a can turn down the temp to it. its just finding the happy spot where it wont overheat the tub or run for hours on end to keep it at my desired set point of 102*.

 

[in hot water]

You need a pump with a check valve, or zone valve to assure you stop the flow completely to the heat exchanger.

In some cases you may need check protection on the supply and return piping, or a pump with a check on the supply and a zone valve on the return, to the HX to prevent ghost flow.

hr

 

[LeonMSPT]

Bob for lobstahs?

Not so bad. Just make sure you approach them from behind... Oh, and don't try it after the pot's already boiling.

Seems so having a heat exchanger, with a circulator or zone valve, it would not be too complicated to pipe up a hot tub.

I am grateful that this thread has appeared. I will soon be hooking up my hot tub and I am going to have to get this right. My wife wants 103*. Not 102* or 104*. The WAF on this is very high. I would rather bob for lobsters than screw this up. :ahhh:

Robert

 

[2.beans]

piping to the tub is a piece of cake. having it stay exactly to temp with all the different hot tubs out there is another story. im trying something new tonight, hope it works.

 

[BrownianHeatingTech]

If i knew where my first over limit thermostat was i could disconnect it this would help some

Find the wiring diagram in the manual, and start searching. That's the best bet, in most cases.

Joe

 

[Bad Wolf]

I was going to do something similar but hadn't thought about weather the system was smart enough to notice if only a 120 vac relay is being used instead of a 240 vac heater.

Where can I get a 240 volt relay cheap?

Also, I built a PVC/copper HX similar to NoFossils. Will the PVC take the full temp 180 water from the boiler or should I get a tempering valve and set it for 130?

Thanks

 

[Nofossil]

I was going to do something similar but hadn't thought about weather the system was smart enough to notice if only a 120 vac relay is being used instead of a 240 vac heater.

Where can I get a 240 volt relay cheap?

Also, I built a PVC/copper HX similar to NoFossils. Will the PVC take the full temp 180 water from the boiler or should I get a tempering valve and set it for 130?

Thanks

I run the 180 degree water through the copper, not the PVC. The PVC has the hot tub water, which is much cooler and NOT under pressure.

220vac relays are more or less a commodity item. Digi-Key has many for under $10. Sockets with screw terminals are nice, although I just soldered the wires onto mine.

I can tell you from first-hand experience that if you accidentally use a 24vac relay for this application, it will have a very short service life ;-)

 

[Bad Wolf]

Thanks Nofossil, yes I will be running the boiler water through the copper and tub water through the PVC, my concern was where the copper passes through the PVC. I threaded mine through the PVC and used pipe dope. Would the PVC get soft with 180 water gong through the copper? What I'm hearing from you is "no".

 

[BrownianHeatingTech]

Thanks Nofossil, yes I will be running the boiler water through the copper and tub water through the PVC, my concern was where the copper passes through the PVC. I threaded mine through the PVC and used pipe dope. Would the PVC get soft with 180 water gong throught he copper? What I'm hearing from you is "no".

The PVC will soften. The hotter it gets, the softer it gets, even when comparing it at freezing versus room temperature. Since it's under no real pressure, it will not get soft enough to be a problem, when going up to 180.

Joe