Danfoss valve

I am almost ready to plumb in my AHS130, and I have a couple of questions.

1. Is it recommended to use a danfoss valve when plumbing the system into the circulation loops? My old wood boiler required one so that cold water didn’t rush in and crack the vessel, lest I void the warranty. Not sure if we need one here or not.

2. The dump zone aqua star located on the boiler—I already have a dump zone in the main circulation loop, left over from the wood boiler. Because i already have one, I am considering using the dump zone aqua stat on the boiler to control the main continuous loop circulation pump—maybe set it to turn the circulator on at 140 degrees and above and off if below 140–those were the settings on the wood boiler I had. Does anyone know of that aquastat would function well in this capacity?

That is all for now...I am sure I will have more later.

What is a Danfoss valve? A mixing valve perhaps...

I'm heading into my eighth heating season, I have zone valves on 4 zones, and I don't even know what a Danfoss valve is. I have an S-130 Coal Gun. I do not have a primary/secondary setup. My circulator turns on only when a zone valve opens on a T-Stat call.

Yeah, danfoss is a big mixing valve on the output water line that keeps cold water from rushing into a really hot boiler. Wasn’t sure if it was recommended or not. I have a primary loop that runs all the time (into a side arm heat exchanger on my hot water tank). The copper loop runs through my basement and the heat from the pipes warm the basement enough to make it somewhat comfortable. I do not have hydronic heaters otherwise in the basement. My secondary loop runs off the main loop, has its own pump and 4 zone valves. Thermostats activate the valves and pump. It isn’t an ideal system, but it works. I don’t really feel like reinventing the wheel in that regard, as it would be a significant plumbing job to replace that setup.

I do have a 3/4" Differential Pressure Bypass Valve (DPBV) on my system, and it effectively acts to send hot boiler water into the zones returning stream to temper it before it returns into the boiler. In a perfect world, when only 1 zone valve is open the DPBV is wide open. When 2 zone valves are open at the same time the DPBV is about 2/3 open. When 3 zone valves are open at the same time the DPBV is about 1/3 open. And when all 4 zone valves are open at the same time the DPBV is closed.

The easiest (non-mathematical) way to set this is to initially set the DPBV to a really high spring tension setting so it will not open at all, even if the circulator is running and no zone valves are open (I.E., when the circulator is deadheading). Then set all 4 T-Stats to come on so all zones are calling for heat, and while feeling the DPBV return line just below the DPBV with one hand, loosen the DPBV's spring tensioner nut incrementally and slowly with the other. As soon as you feel the DPBV return line get hot, reverse what you have been doing and tighten down just a wee bit on the spring tensioner again. This sets the DPBV to be just barely fully closed for the case of all 4 zones open. The rest (I.E. the perfect world stuff) is then totally up to the action of the spring actuated valve plunger. This will only work for the case of a single fixed speed circulator. And this method will likely not work for PEX, as it will not heat up instantaneously as does copper. Setting the DPBV for the case of PEX requires a mathematical spring tensioner setting solution method.

The intent is to provide essentially constant flow pressure (and thereby flow velocity) within each zone for the case of a single circulator and zone valves.

What do you have for heat emitters? Baseboard, hydro coils, cast iron radiators? Tempering the return water isn't as important for low water content emitters.

David

Trumpeterb wrote: ↑

Fri. Aug. 09, 2019 11:08 am

Is it recommended to use a danfoss valve when plumbing the system into the circulation loops?

Just so you and everyone else knows, Danfoss is a company, NOT a type of valve. It would be helpful if we knew where this valve was installed.

Basically, at the boiler you should put a bypass pipe from supply to return with a manual valve in it. Install a PRV and pipe it down to the floor. Then run the supply side to the supply header and the return side to the return header. If you have another boiler in the system it gets a little more complicated.

You need to look at the AHS install manual. I would hope that all this is covered in it. If not, you can go by and Axeman, EFM or Van Wert install manual. At least for the boiler part, they are all the same.

-Don

David... wrote: ↑

Fri. Aug. 09, 2019 3:47 pm

What do you have for heat emitters? Baseboard, hydro coils, cast iron radiators? Tempering the return water isn't as important for low water content emitters.

David

In the main floor of the house I have radiant zones in the floors. In the basement there are no heat emitters. Just the copper pipes coming from and going to the boiler.

Since you already have the mixing valve, it makes sense to use it. Another alternative would be a small (20-30 gallon) 4-way buffer tank through which the primary loop passes and off of which the zone loops are fed, and to which the zone loops return.

This is similar to the valve I have

https://www.supplyhouse.com/Danfoss-193B1701-ESBE ... 8MQAvD_BwE

No issue leaving the system piped in the current configuration with the mixing valve.

Anyone have thoughts on the other part of my OP? Using the dump zone aqua stat to run the “always on” circulator?

Dan Foss thermic valve is a requirement here...not just an option.
Typicaly a mix or thermic valve is in a radiant floor system to reduce normal high boiler temps to the much lower temp need for radiant floors...the typical 180* water is way too hot for radiant floor heat...thermic not there so much for low temp 'shock' of boiler...but that it does as well.

Trumpeterb wrote: ↑

Sat. Aug. 10, 2019 9:17 am

Anyone have thoughts on the other part of my OP? Using the dump zone aqua stat to run the “always on” circulator?

What's the model number? An l4006b operates on high limit only (many use as dump zone control). An l6006a does both high and low and would work as a constant loop control to turn the controls on for a low limit set point...

l606a. The sticker placed on that thermostat by the AHS factory said high limit.