Troubleshooting System Upgrade (pump board, flow system, boilers?)

NJradiantnewb

I purchased a home that came with 8 zone staple up radiant (closed loop system). House was built ~2003, is about 6,000 sq ft. All major equipment is original (pumps have been replaced over the years as well as storagetank). We've been in the house for a year and our energy bills are awfully high (over 6,000 kWh in a month in the winter). Temp for radiant on thermostats is set to 72 (water temp off the boilers is 120 degrees).

Flow system for each unit uses 2 x Grundfos 26-99 pumps

Radiant system uses:
2 x Waterfurnace Versatec VX060 boilers (5 tons each) - units each have a Grundfos 26-116F circulator pumps bringing water back to the units
8 x Taco 007 Circulator Pumps (3 zones on main floor, 2 zones on second floor, 1 zone garage and 1 zone above garage)
Loops appear to be 200 ft in length (based on loops in the basement that note they're 200 ft)
One of the units also does chilled water for a room above the garage in the summer for A/C, but we don't really use that room so A/C is usually off.
60 gallon water heater for storage

Radiant floor heating is supplemented by 2 water-to-air units (that do heat in weinter and a/c in summer):
1 x 4 ton unit for the main floor (Waterfurnace Synergy RTV046)--hydronic stage is disabled; and
1 x 3 ton unit for the second floor (Waterfurnace Versatec VXV036)

A few observations:
1. The radiant system has a 30 degree delta between water temp leaving the boiler and water returning from the zones, which seems pretty high. Not sure if the system was designed this way though.
2. One of the zones (which is the room right above the boilers) is poorly insulated, so radiant can't keep up with temp loss and circulator pump runs non-stop. I've looked and there's normal insulation (with foil) below the staple up PEX, but strikes me as odd that a taco 007 pump can't handle it
3. Second floor has a lot of problems being served by radiant only. When it's cold out (below 30 degrees), indoor temp for second floor zone can barely get above 68, basically circulator pumps run 24/7 and don't get the rooms any hotter. Thought is maybe a bigger pump could resolve issue on second floor.

Had the contractor (who's currently servicing the units) take a look at the system and come back to me with a menu of items, but since I don't know what exactly the issue is, it's hard to tell what's worth upgrading/fixing. First thought is the new flow center and pump board but not 100% sold on ECM cost savings relative to initial outlay.

Any help would be much appreciated.

EBEBRATT-Ed

OK, so the pumps run non stop which makes me think of a flow problem. What about the equipment? How hard is it running?

You could start from scratch. Do a heat loss of the home to get the BTUH/hour needed. Check that total against the installed equipment. If that matches up the next stem would be some calculations with regard to your loops, can they provide the needed heat?

This will lead you in the right direction as far as troubleshooting. Jumping in to the middle does no good.

They you will know the best bang for the buck

Jamie Hall

A BTU is a BTU. And it is quite possible that the radiant system, with those water heaters, simply can't keep up with the heat loss on colder days, or in colder parts of the house. The 30 degree delta T is a little high, but not really outrageous. increasing the flow would decrease that, but wouldn't give much more heat to the space. It's a tradeoff.

On the colder spaces, you're kind of stuck. 120 is about as high as you can run the water temperature for radiant floors and, as I note, increasing the flow (bigger pump) will reduce the delta T, which will get the floors a little warmer, but may well not be enough difference.

Can you do anything to reduce the heat loss of the house? More insulation? Better storm windows? Draught sealing?

Ironman

Some pics would be helpful.

hot_rod

Describe the staple up. bare tube stapled to the floor? Or tube in aluminum transfer plates. send a pic or two.

NJradiantnewb

NJradiantnewb

Here’s the insulation with the staple up.

NJradiantnewb

Bump

hot_rod

Yikes 8- 80W circulators and 10- 245W? What is the heat load of the building?
Pics are dark, looks like a rubber tube stapled to subfloor?

Heat pumps do not supply warm enough fluid for those bare tube staple up, in some cases.
The best first step would be a room by room heat load. 10 ton of GEO?

NJradiantnewb

10 tons of Geo for the radiant. Supplemented with water to air from another 5 ton unit downstairs and 3 ton unit upstairs. I guess I could get larger boilers (7 ton each) for floor radiant but am curious if I would see savings from installing a new flow systemsor getting new pumps board with 2 large pumps and valves (magnas) for the entire system before replacing the big ticket items like the boilers.

Jamie Hall

Start off with figuring the heat loss of the building, as @hot_rod said. One way or another, you then have to come up with enough heat input -- heat pumps, fuel fired boilers, whatever -- to meet that requirement.

If you can increase the efficiency of the boilers or the heat pumps, then -- and only then -- can you expect to see any savings on energy. Different pumps and controls will only make a difference if the current ones are malfunctioning in some way.

NJradiantnewb

I've gone through and done the load calcs and here's where I'm coming out:
1. As far as total BTUs for entire system, the 17 tons for the entire house is the right amount, but the split for those BTUs seems to be off.
2. Radiant BTUs required are about 13-14 tons whereas system only has 10 tons, so while a combination of the radiant + hot air works, radiant system doesn't deliver enough heat to serve the rooms it's in.
3. As far as cooling, 4 ton first floor and 3 ton for second and third floors), this seems undersized as well, but the house is cool in the summer.

So the questions are:
1. What upgrade would be the least costly but yield the highest savings? New pump boards, flow system, hydronic boilers, or water to air units?
2. Given cost for everything, and limited effectiveness of staple up pex should I scrap the radiant and just upgrade the water to air units to larger sized units for heating and cooling?

Jamie Hall

Critical piece of information, without which commenting is pretty hopeless: what is the Formula J heat loss of the rooms in which the radiant is located, and what is the floor area of those rooms which is heated with the radiant (not covvered with rugs or carpet or cabinets etc. -- actually has loops under it).

The reason for asking is that there is a definite upper limit on how much heat a radiant floor can provide, and one needs to know whether it can actually do it at all, before thinking about upgrades or changes.

Rich_49

Where in Nj are you located ?