Saskatchewan Floor Heat

I hear you.
Get another distributor, and put a 1-2 Wilos in stock. I always have a few laying around. They are variable speed, one size fits it all.
You can simply set the pumping power.
I get none of my stuff in Buffalo, none of the high tech stuff is available at the local supply shops, have it all shipped. UPS and FedEx make is possible.

 

Doc,

I have looked at your WEB site and some of the systems you have profiled and have come to respect your expertise. That's why your comments really get me wondering what sort of distribution system I had designed for me. The main circulation pump comes on anytime one of the zones is active. I always assumed it was necessary to pre-load the manifold and return the water back to the buffer tank. As for each zone circulation pump if I didn't have the zone pump I would need some sort of thermostatic zone control valve to know when to direct fluid to the zone loops. Valves sound cheaper than pumps but at this point there's not much savings in putting $1400 worth of pumps on the shelf. I do agree the zone pumps, whether needed or not, do appear to be the wrong type of pumps. As I mentioned before I believe they should be delta T type pumps. Thanks for the note about the TeKmar product, I've added the brochure to my file and will keep it in mind. Again, Thanks.

 

It does not matter if the zone thermostat in your living room or bedroom turns on a pump or opens up a motorized zone valve with its 24V signal.
Yes much cheaper to use valves.
However, it is not the the $1400 for the pumps which are the issue, but the hundreds of dollars each year to run them! This issue magnifies when you lower your supply temperature for higher efficiency, now the run time of the pumps even increases, nullifying your savings.
Not sure what you refer about delta T pumps, since I do not know any delta T pumps, unless there is a temperature sensor on the supply and the return, and you can dial in a delta T for the zone?
With a variable speed constant pressure pump (central pump) you can dial in your pressure, which determines your flow, which determines your delta T. In other words, the pressure on the pump will determine your delta T and keep it stable, no matter how many zones are open.

 

delta - T is an option different than delta - P.

Taco is the main player in the delta T world.

 

Doc,

You are just full of 'glad tidings and cheer ;-)' but you know you're right. I'm an old miser at heart and I do think of the dollars I'm burning when I look at my seven circulating pumps and then again when I think of those Copeland compressors running at less than the desired COP. If I had the money I would start over again; maybe Santa has a spare distribution system in his bag;-)

I know there is something called delta T variable circulation pumps. Taco 00 series is one of them though I must admit I'm not sure how they work and I must admit that unless I win the lottery I'm not sure what more I can do to make any improvements. I'm afraid you're right, as I play around and drop my temperature if it still keeps the room warm it's going to be because the system is circulating water longer. Longer circulation time means longer pump time including the buffer tank pump which would probably kick in a few extra times.

Hey, anyone know where Santa is?

 

Bob,

Your primary/secondary plumbing layout is not really of value to your usage - as you've noted. It is generally used when dealing with multiple temperature requirements in a system. You can have multiple boilers (propane, geo) providing at different temperatures; multiple loads (fan coil, floor zones) using those loads; and controlled mixing of boiler waters. It provides hydraulic separation that allows those types of systems to be more optimized.

In your case, it is likely a bit of a detriment, as it greatly increases the number of pumps you have. A homerun layout on a variable speed would make more sense from afar. If you know your flows, you could figure out if it's worth combining branches on to shared pumps. And then splitting the primary loop into a supply/return header. Would I do it? Maybe. If I didn't have to buy new pumps. And the existing pipe sizing made sense. I know I have way too much other stuff around my own house I've fallen behind on.

 

See I learned something, there is such a thing as delta T circulators.

I cannot come to see their role, since the radiant system must be grossly unbalanced for them to make sense. We are going more and more towards low temperature applications, since this is the wholly grail of heatpump efficiency, thus flow becomes more and more important, and with lower supply temps, and lower delta Ts.

It does not matter too much for heat transfer if a certain radiant system runs with a 4, 6 or 8 degree delta T. Plus with increased flow, unbalanced circuits will balance themselves out.

 

I have systems with either and/or both. Delta P's on source side. Delta T's on load side.

I look at it the other way. The only reason Delta P's exist for our world is to shed a certain amount of btu's in a zone and staging flows. They also had been in existence for other uses. Delta T's skip the middle step and just measure T directly to get there.

Now delta P's play their role well in working with equipment that absolutely has to have certain flow.

At the end of the day, they both can get there. It's just when I do all my number crunching, the pressure drops no longer matter to me after initial pump/pipe sizing. For comfort, I'm back to thinking about those btu's and I know they're getting into the zone based on that temp drop. Adjusting them after installation also is simplified as original design doesn't really need to be in hand.

T or P, they both sit on the same flow equation. Especially when little flow meters exist on the manifolds

 

I find all the various comments quite helpful in adding to my knowledge base and help me understand my system. I wish I would have had this knowledge when I first began talks with the firm that designed my system.
It has become quite apparent to me that I have a distribution system that is less than optimal but I'm beginning to get the impression that perhaps my biggest detriment is restricted flow. With one exception I have 1/2" Pex throughout which should support adequate flow. Although they may not be the most optimal pumps I believe they can move enough fluid to do the job and although a Primary/Secondary distribution system isn't the best choice it could be made to work. I'm inclined to think that I could see some gains in BTU output if I could increase the flow. I think my big limitation is having manifolds that have a maximum flow rate of about 1 gpm on each port. Any comments?

 

Why don't you take some picture of your system. I did not even catch your primary/secondary system......bad news again.

 

Thanks for the interest. Attached are three pics. Split the board in half for a bit more detail. Also one of 5 manifolds. The largest is 7 ports.

 

I can see the variable P on the source side. Don't see much sense for either on the load side.
On the load side, none of the zones must have a certain flow. You need to be in the ballpark, which you know you are when you have a certain delta T. As you said so well, the BTUs are getting in the zone when you see the temp drop. I am with you.

Once you are there, you start to ask hoe to do this more efficient and simpler. That is when usually when a central variable speed, constant P pump comes into play.

 

Whoever designed your radiant system lives in an old boiler world. To have the supply and return from each zone piped in the same manifold, is detrimental to efficiency in a geo system. Since the water will come back from each zone cooler, the further down the manifold you go, the cooler your supply temp gets.
In order to get any warm water into the last zone on the manifold, you must increase your water temps going into the manifold, and to raise the water temp will significantly decreases your efficiency.
There is too much inefficiency in here, it gets to the point where I would consider redoing your manifolds and your pumping solution.

 

Doc, I have been giving a lot of thought to the inefficiencies of my system and am considering trying to put together a budget and possibly make some modifications in the new year. You suggested in an earlier post that I would be better to have one variable pressure circulation pump and five zone valves. I am wondering what you would suggest as a suitable pump and zone valves. I did a bit of research and the Taco Bumblebee looks like a possible pump and taco Geo-Sentry seems to be the only suitable zone valve I could find. Do you or anybody else have any recommendations? Thanks

 

I would use one of your constant speed pumps between the heatpump and the buffer tank, which I don't see in your picture (buffer), and then use a Wilo Stratos as a variable speed.
Not a big fan of Taco pumps, but their zones valves are fine, alternatively the Belimos are very good as well. Both are designed for low pressure drop.

How many BTUs are you trying to send to your zones? How much flow per zone.

The image I sent you is a high resolution image of everything you would need, including 2 Wilo pumps and the Taco zone valves.

 

And I know people don't generally have a "tear it all out do it this way" budget, so use your existing variable speeds to determine how many branch circuits you can combine (vs. possibly having to buy a larger variable speed). And re-do the header to be a home run layout vs primary/secondary.

BUT - we're talking fixing energy inefficiencies of an existing system. Not necessarily improving comfort levels.

 

Bob, lets step back here for a second, just tell us what kind of pumps you have here, they look like some Wilo Ecos, which are excellent pumps, and a Wilo star, don't know what your central pump is like, but it looks like a wilo as well.

Also give us a diagram how the circuits are, what pipe size and what length. Including header pipe. And how many BTUs we need to get into into each zone.

What heatpump do you have? Model #?

Do you have staple up?

There is a potential that you can keep the ECOs in lieu of the zone valves, and just change your manifold. Do the ECOs have a check valve?

Could you also get some more pictures how the plumbing is towards the load side of your heat pump.