Underperforming system in cold temps

Sukhoi29SU

@ bjohnhy - also, the supply sensors I was talking about are the blue lines coming out of the top of the taco valves and running downstream of the pumps.

@hot_rod yes you can manually adjust the taco valve to allow full hot water in if you wish - however I’m confused as to why I’m not getting 150 degree water (if the boiler is set to that) to the taco valve to be mixed with colder return water, to produce 130 degree water based on dip switch settings. I’m pretty sure the valve is installed correctly. I might need to look and see how much return water is actually being mixed based on where the valve resorts when powered up. It’s almost like all the hot water is going to the manifold without being mixed with any cold, and it’s much less temp than what the boiler is producing.

bjohnhy

Looks like that taco mixing valve is already oriented to the full hot position, I don't think it is your problem (you already figured this out, I bet ?).

So your not getting high enough temps out of the boiler. Is your boiler set up for outdoor reset? Is the outdoor sensor in an ideal location (not by any source for heat, exhaust, vent, etc)?

hot_rod

the temperature in or at the boiler may not reach the manifolds due to the hydraulic separator. There is some temperature blending taking place inside.

If you want 150 at the manifold the boiler or system sensor needs to be placed downstream of the sep, where that temperature gauge is. Then the boiler will run to whatever temperature it needs to supply 150 at the mix valves. If in fact you need 150 at the mix valve. I would think if you need 110 and you have 110 at the mixer, it would go full open, no mixing. But I don’t know how that valve control logic works?

Sukhoi29SU

https://forum.heatinghelp.com/discussion/comment/1836940#Comment_1836940

Well, based on putting my hand on the copper prior to the taco valve, and then putting my other hand downstream of the taco valve and pump and them feeling the same to the touch - I determined that the valve isn’t mixing much , if any, cold water into it.

I did some parts of the system Install but I did not do any of the wiring. I asked them to put the outdoor sensor underneath a cantilevered area of the house, no exposure to the sun on the east side of the house; it should be clear of any exhaust or hot temps there - but I will confirm tomorrow.

I’m thinking it has to be a sensor or some hidden boiler setting.

I’m thankful the system is performing nicely despite the cooler water temps at the manifold -even during such cold outdoor temps. I’d really like to see what it’d do if I could get 120+ degree water there.

I’m interested to see what water temps I get at the manifold when the temp warms up outside

Sukhoi29SU

https://forum.heatinghelp.com/discussion/comment/1836944#Comment_1836944

There’s a temp/pressure gauge on the copper pipes right out of the boiler just past the T to the DHW tank. Prior to the caleffi hydraulic separator I’m getting just shy of 120 degree water. After the hydraulic separator it looks like I’ve lost about 5 degrees or so. It’s indicating between 110-115 just prior to the taco valves . (Pic above) .

Then it hits the taco valve where it appears the vast majority if not all water passes through without being mixed - then I’m down to 90-100 degrees at the manifold.

I don’t believe there are any sensors installed prior to the caleffi, only gauges. Unless there is a sensor in the boiler itself. The only sensors I’m aware of are the two connected to the two Taco three way valves, and the outdoor temp sensor

hot_rod

if it enters the mix valve at 115 and out the mix port at 100, there must be some mixing going on? Maybe that valve cannot shut the cold side off 100%?

I use strap on thermistors on a Fieldpiece meter to get fast and accurate readings

Too much operator and surface condition error with point and shoot temperature guns, if that is what you have?

Sukhoi29SU

@hot_rod it enters the caleffi at hydraulic separator at a little less than 120, it exits the caleffi at a little less than 115. The Taco valve is next, and it appears that the temp prior to and immediately after the taco valve is the same (I don’t have a temp gauge right after the taco valve - although to the touch the copper feels the same temp)

I might not be understanding the system properly - I’d think that if I had the boiler temp set at 150 that the 150 water would lose a little temp passing through the caleffi but deliver 140+ water to the taco valve, and based on the dip switch settings the cold return water would mix with the hot water to produce 130 degree water (max allowed based on dip switches) and I’d get 120 ish degree water by the time it reached the manifolds.

Instead, the water out of the boiler , regardless of being set at 150, has a little less than 120 degree water being pushed through the primary side.

Does outdoor temp sensor regulate the temp of water leaving the boiler regardless of boiler temperature setting? I thought the taco valve was supposed to regulate the supply temperature to the secondary solely by adjusting the three way valve to mix the cold return water with whatever (or very close to) boiler temp setting water, based on Taco dip switches and reset ratio dial setting.

Bottom line - something seems to be restricting the boiler from delivering the water temp selected at the boiler.

For domestic hot water, the boiler fires up to 185 or so (also adjustable at boiler) and that pipe gets very hot leading to the domestic hot water tank. But the 150 for floor heat isn’t delivered. Even when I set the floor heat boiler setting to max it still seems to produce the same temp water to the taco valves (less than 120) and it just might not fire up for as long.

I assume that when it’s really cold out you’d want hotter water at the manifolds - but I might be misunderstanding how the system should work because it did do a nice job keeping up today. At -13 this morning I noticed that many zones were calling for heat but they were only shy of the thermostat settings by a couple degrees and that improved through the day.

Thanks again for all the help

Sukhoi29SU

today the outdoor temp is 19 degrees, considerably warmer than yesterday - and now I’m getting warmer water to the manifold - it’s registering 105 at the manifold. It appears the warmer the temp is outside the warmer the water to the manifold is…

hot_rod

Just looking at the control module, multiple knobs, this boiler probably has ODR outdoor reset function. Is that being used, a sensor mounted outside on a north wall, for example? That would explain the varying SWT temperature

That control display screen or info screen should tell you boiler supply, boiler return, and maybe boiler target, the temperature it is trying to get to? The operation manual would tell you how to access that info. Those would be the most accurate measurements as they are usually probes into the fluid stream, not strap on.

In my mind if the 3 way valve has 110 or whatever in the H port, the mix port, or AB port should be able to see 110. There should be no blending if the valve closes off the cold, or B port?

If the thermostat satisfies before the boiler reaches the setpoint temperature, you may not see the target temperature being reached. The load is satisfied, the boiler should ramp down.

At days end, are you warm and comfortable now and at the coldest days? If so you may not need to screw with it?

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hot_rod

Sometimes the smaller bottles end up being less $$ if they are on sale. Recycle the bottles.

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bjohnhy

https://forum.heatinghelp.com/discussion/comment/1837123#Comment_1837123

This is wrong thread? I do it all the time

bjohnhy

What you are describing is consistent with the boiler being controlled by an outdoor reset (separately from the Taco mixing valves ODR). It sounds like the system is working perfect?

https://forum.heatinghelp.com/discussion/comment/1837105#Comment_1837105

Also, those TAco iseries ODR 3-way mixing vavles are capable of going to either full hot or full cold. When that black knob is vertical as in your photo, that is full hot. When it is horizontal, it is full cold. Somewhere in between is a mix. When I need to manually test it, I don't use a screwdriver. I just push it in and twist with my fingers (kind of like a prescription pill bottle).

hot_rod

https://forum.heatinghelp.com/discussion/comment/1837206#Comment_1837206

sorry right church, wrong pew

Sukhoi29SU

https://forum.heatinghelp.com/discussion/comment/1837209#Comment_1837209

@bjohnhy

the system has been working great now as far as keeping the house and garages warm. It just works differently than what I’d expect. The way I understand the reset ratio to work is as the outdoor temps get colder, the water temp supplied to manifold gets hotter. I haven’t seen that. If the dip switch settings are set to allow max of 130 degree water through the taco valve, why wouldn’t I see hotter water getting to the manifolds when it drops into the single digits outside?
you mentioned that perhaps the boiler has its own outdoor reset separate from taco valves ? I probably need to dig into the boiler settings and look into that.
again, system is working great now that I have sufficient flow through the floors - now I’m just trying to make sure it’s running as efficiently as possible.

when I checked yesterday the supply water was about 90 degrees and the return water was 85.

Thanks