Groundfoss Alpha, home runs and TRVs

Tristan

I'm building a home run system to 8 cast irons rads with TRVs.  I have a question on how to wire the Groundfoss Alpha because I'm looking at having running constantly.  That's the whole point of the TRV's, right?

My understanding is that radiator/TRV would open, and the Alpha would need to be pumping to provide the heat needed.   Then, as the water temp began to fall, the system temp sensor would pick up on the water temp drop and fire the boiler and turn on the boiler pump.

 Wiring the Alpha to the boiler will tie it to when the boiler goes on and off - which with my control scheme, is not what I want, I think.



Do you know if the Tekmar 260 has a option for powering the circulator 27/7? However, it would be great to have the pump to shut down on warm weather days. What do you think? Is Tekmar control the answer?

Tristan

Help needed

Nobody responded to my previous post, I guess it must be  pretty unclear... but hopefully someone who knows Grundfos Aplha and TRVs will understand what I meant. As you can see, I need help. Thanks!

Gordan

How are you piping this?

The answer will depend on that. Do you want the Alpha to block during a DHW call or should it continue (as would be the case if you're pumping from a buffer?) At its simplest, the Alpha could be on all the time, controlled by a simple wall switch. It only uses something like 3W on standby.

A.J.

Alpha circulator

Tristin just wire up the Alpha and leave the power on to it 24/7 , as your TXVs open it will speed up to deliver more flow. The same will happen as they close. All you need is something to turn on the boiler. Whether it be an end switch or reset controller, the Alpha will adjust to the system. 

A.J.

Tristan

More details on the Alpha

 Yes, I would be pumping through a buffer tank. Is there a way to have the Alpha run most of the time but would shut off when days are getting warmer? Do you know if a Tekmar control would do this as well as controlling the boiler? Or do you think it is not worth it and I should just have it on a switch?

Thanks

Zman

The alpha..

The alpha has a plug factory wired. It is easy to wire it 24/7.

The 260 is set up to run a boiler pump. It may be possible wire the alpha into this.

How are you piped? Do you have a primary boiler circ? Does it run during dhw and heat calls? What type of boiler ? Ar you trying to do domestic priority?

Carl

Tristan

Trying to design a simple system

@Zman and others, you just pinned point were I'm currently struggling. Boiler is Burnham RV5. I don't have a set design yet for my system. At this point, I piped all the radiator to the manifold. I have both a pluged feed with a circulator and a plugged return pipe from the boiler, which are from the previous base board system. The only thing that is running from my boiler right now id DHW.

 I know since the Wall people help me figure it out, that I need to put a buffer tank on the system. So here is what I thought I would do. I would remove the old circulator, would run the 1" pipe feed pipe from boiler to the top of the buffer tank, in  and out. Then I'll place the Alpha circulator between buffer and manifold input. For the return, It will go from manifold to some type of dirt/particles separator (Spyrotrap). Then to the buffer tank in and out and back to the boiler via an expension tank. Does that make sense or am I totaly wrong?

Thanks again, Tristan

Zman

That may be..

That may be the worst I&O manual ever.

Could you post a picture of what you have so far, including the boiler circ and any valves inside the cabinet. It looks like there is a bipass valve installed on the boiler but you can't tell from the manual.

What are you planning on for a buffer tank. Something with 4 ports for hydraulic separation or just a 2 port tank?

Carl

Tristan

Boiler

@Zman, why can't I just reuse the old 1" supply port on the boiler that was previously used for the baseboard loop? Other than this, what do you think about my system design. Is there any flaws that I should correct or change?

 I will use a 30gal buffer tank with 4 ports.

Regards,

Tristan

Zman

Picture?

I don't know how your system is piped.

Carl

Tristan

More info

Thanks for the help, Wall people, I'm making serious progress in how to retrofit my boiler from baseboard to cast iron rads. I'll post pictures of my boiler later today or tomorrow morning. Here is the simple heating system design that I want to replicate. Because my boiler (Burnham RV5) is 100% oversized, short cylcing will happen, especialy if I'm using the Tekmar 260 to control the system. To provide more heating masse to the system, I'll  add a 4 ports buffer tank on the line. Should my circulator be placed before the buffer or after the buffer? What about the expension tank for the buffer, should it be placed after the buffer  on the return pipe (colder pipe)? Do you see any other thing that I should be aware of and are not well represented on the drawing? Thanks to all,

Tristan

zacmobile

260

Yes, if you wired the Alpha off the 260 it would keep it on any time the outdoor temperature falls below the warm weather shutdown point selected in the control. However, for some reason grundfos recommends keeping it on all the time, maybe the pump might forget it's settings over the summer or something.

Gordan

AutoAdapt

It's AutoAdapt that doesn't like power cycling. Any of the other modes are fine with it.

zacmobile

piping

I would pipe it exactly as shown it the schematic you posted only replace the boiler with a buffer tank. Does your RV4 have a built in boiler pump? If so you would simply pipe the supply to the top of the buffer & return to the bottom with maybe a tridicator on the supply somewhere.

Tristan

Buffer tank

Here is a picture of the buffer tank that I plan to buy. It is a simple 30gal hot dipped galvanized tank at less than half the price of Boiler Buddy. Of course, I'll have to insulate it myself, but I think it is still a better deal. Now, do you guys think that I should use the two  ports "E" on top for feed pipe and then the 2 ports  "E"  at the bottom for return? Or   should I use "F" and "E" at the bottom? Thanks,

Tristan

SWEI

buffer tank

You really want hot at the top and cold at the bottom with boiler on one side and load on the other.  Assuming there's no dip tube, I'd stand it on end and use the two tappings nearest the bottom for cold, and the top side plus the far top tapping for hot.  Put an air vent in the other top tapping, and include a drain tee on at least one of those bottom pipes.  Stand it on a piece of 2" XPS foam before you pipe it up - then you can spray insulate in place.



Proper control of water pH will be critical if you're planning on pairing zinc with copper.  I wouldn't, personally.

Tristan

how much concerns?

"Proper control of water pH will be critical if you're planning on pairing zinc with copper.  I wouldn't, personally."



Is there anyone else that share or not this opinion? How concerning is it knowing that I have city water?

hot_rod

tanks

you can buy a tank like that in painted steel also. They are sold as compression tanks. I haven't seen any pre-made tanks that have all the correct sized tapings in all the locations you need, however. I've been on a life long search for ideal buffer, or buffer/ separator tanks.



When it is all said and done a nicely constructed and insulated, factory tank built for the task may still be the best option.



It's tough to insulate and jacket a plain steel tank as a DIYer project.



I don't think the galvanized tank would be an issue if you figure out how to connect the copper to it. Typical dielectric unions are rated to 180F, or build some isolation flanges.



hr

Tristan

More about the tank

Can I use something similar to this to break the flow of current to prevent stray current galvanic corrosion? Any other concerns I should pay attention to with a galvanized tank?