Pumps vs Zone Valves

Mike_Brooklyn

I am building a new house and need to decide between ZONE PUPMS and ZONE VALVES for my heating system.  The house will have a total of 9 zones (see attached diagram and floor plan).

Zones: 1, 2, 6, and 9 will be RADIANT HEAT.

Zones: 3, 4, 5, 7, and 8 will be ALUMINUM RADIATORS.



I spoke to several contractors and  getting conflicting opinions: some advocate 9 pumps, others say it is a waste and advise only 1-2 pumps...



Can you guys offer some insight on the preferred solution, as well as pro/cons.



Thanks a lot!



Mike

Zman

Alpha

I don't know of a zone pump small enough for your loads. You are going to use an incredible amount of energy with 9 pumps.

You should have someone look at your exact requirements, My first thought is a grundfos alpha with zone valves.

I know you didn't ask... Your boiler is to big! Given your small zones and low temp radiation, you would do very well with a smaller mod/con boiler. The high turn down ratio of the mod/con will allow you long efficient burn cycles. Mod/cons love low temps.

The thing to do is have a heat loss calculation done and size your boiler correctly.

Carl

Gordan

TRVs

The alpha would also work well with thermostatic radiator valves placed on the radiator zones. These are typically cheaper than the combination of a wall thermostat and a zone valve, and allow flow through the zone to be modulated according to what the zone requires, rather than the binary fully on - fully off.

Paul48

Boiler

That boiler would be too large for my 1925 home. With new construction, you'll be amazed when you do the heat loss.

Joe Mattiello

TRV

I was surprised to see your alternative to the zone valves, or circulators using TRV.  I agree that it's a good way of balancing the system, right out of Dan's Classic Hydronic book, but is that commonly done today?

Slimpickins

TRV's rule!

I wouldn't say it is  commonly done but for a few of us in the know,  it sure is. I try explaining the concept to others in the trade that aren't familiar and they look at me like a dog that's just been shown a card trick. They can't get past using zone valves. It's so simple if baffles 'em I think.



To the original poster, I'd be looking for contractors that are fluent with modern hydronics. The boiler show on the plans is last century technology and I'm sure way over sized.  Check the Find a Contractor tab at the top of the page for someone in your area to help you out and keep checking back here on the Wall.

The Steam Whisperer (Formerly Boilerpro)

What I'd suggest

all of your radiators should use TRV's and a single pump.  Most wall hug radiators are designed to have the trv head snap right on.  thermostat installation takes about 20 seconds per zone and their is much less piping.

The radiant zones may be able to use TRV's if the tubing layout is correct and outdoor reset is used and would probably need a second pump

I can almost guarantee the boiler is grossly over sized,  I have a 1905 two story frame with 3200 sq ft of 8.5ft tall living space, 800sq ft of windows (700Sq ft original with storms)  and need less than 50,000 btuhr  gross output to heat my home in northern Illinois.



I think you really need to find someone that knows hydronics.  If your in Chicago, give me a call.  I have also been doing hot water for 20 years.

radmix

TRVs

It is my experience that TRVs constantly break down. I had a customer that had me remove all TRVs from project because he was replacing at least one a year. Zone valves are more reliable.

radmix

TRVS

Sorry Delete that last post, TRSs are great I was confusing them with actuators. It was to early in the morning for Me to post.

Paul Pollets

Zoning

I'd be using a motorized 3-way mixing valve for the radiant load and zone valves for the radiator load. I'm not fond of aluminum BB because of it's low output, compared to properly sized wall panel radiators. I'd use a "smart" pump like the Grundfos Alpha for both loads, and use a modulating condensing boiler, rather than a cast iron. The mod-cons are very quiet compared to a cast iron boiler that is power vented. If the radiators are sized for a condensing load (usually 30-35% larger) they will be able to heat the space at much lower temps. I always use TRV's on wall panel rads and control the zoning at each radiator.

Less piping, fewer controls and more efficiency. If you're in Brooklyn, there should be a heating contractor that has the design background and expertise to give you a better system.