Newbie: Foreclosure with Electric Boiler/Hydronic Heat

whitt_travis

Hey guys,
My name is Travis and I'm a teacher located in northern MN where temperatures in Dec-Feb can typically dip below zero. I'm going to try to plug as much information as I can to try to get the the help I need!

Problem: Previous owners are saying they're consuming $700 and at worst case $1000 dollars a month in electricity during our miserable winters. Below you'll see my rate schedule for my area. Off-peak as mentioned later in the thread.



House: Foreclosure (eeeek right?) 2003, slab home with 2 inch insulation around the perimeter. I can't verify if there is foam insulation under the slab, but there wasn't lots of snow melt around the perimeter of the home when viewed on a -22* below day or a 32* day. Soil is loam, drainage appears good, gutters all around. 1900 sq ft, with bats & blown in fiberglass insulation in the attic (not ridiculous amounts but above rafters). No insulation on the roof deck. 2 stall/2 door Garage is ATTACHED and HEATED with the hydronic system.

Hydronic: Thermolec system is a 92,000 btu/27kw electric boiler, off-peak. Manifold is not zoned, but does have the ability to close valves manually with ball valves. 8 pairs of outflow and return lines. System does not feed house hot water and is a closed system. Below is a crappy picture so hopefully my explanation is better.



Layout: House is a slab build with roughly 26 by 90 foundation size including the garage area (insulated above, what's in the walls I would assume is batt) that is heated by the single zone (ALL ON ONE THERMO, CENTRALLY LOCATED IN THE HOUSE) hydronic system. The boiler and pex tubing is located in the far corner of the garage on the outside wall, and must travel the whole length of the house to reach the back bedroom area. Garage can get ridiculously hot (like 80*) while the back of the house is cold (below 70, I'm assuming, information here is from previous owner.)

THE QUESTION: Do you think the giant loss of energy/the fact that the boiler must be running frequently would be due to the fact of the lack of zoning? Could the proximity of the garage loop to the boiler be the reason it's always substantially hotter then the rest of the house? Could the energy draw from drafty garage doors be the reason the boiler is working hard to maintain water temp in the lines? Or am I possibly dealing with a house with no insulation below the slab? Did the builder skimp on pex to match the needed structure? Would zoning the house & running the garage at a much lower temp, pushing more heat to the back of the house where heat must travel much farther to reach it's destination substantially reduce my energy consumption?

Thanks in advance! I have zero experience with radiant/hydronic systems so insight would be appreciated!

Jamie Hall

Is this radiant floors? Or is it baseboards? Makes a difference. For some reason, I'm thinking radiant floors...

In any event. From your description it is clear that the balance of the system -- the flow through the various loops -- is way off. Can you identify which valves control which areas of the building? Ball valves aren't ideal for zone balancing, but they can be used and, if you can identify which valve does what, you may be able to reduce the flow to some zones which are warmer than desired -- particularly to the garage! -- and save a good bit just by doing that. It would be better to use proper zone valves with thermostat control, however. But the first step is to identify which valve does what.

Now if it is all radiant, you can likely get away with a single water temperature; likewise all baseboard. If it's a mix, it gets more complicated.

It is very likely that installing an LP modulating/condensing boiler could save on energy costs. It is even possible that it could save enough to pay for itself in a reasonable length of time.

whitt_travis

Radiant hydronic in floor heat, yes thanks for the info, we were thinking LP/Propane boiler and a modulation system may be the best answer (wood boiler is also an option, but propane can be had cheap + a huge tank).

My hope is that the lack of balance and regulation in the temperatures is the biggest culprit to why those bills are so ridiculously high, but I may be wishful thinking.

No idea where the lines run what so ever, or how much pex is actually laid within the concrete. To find the possible zones, I could wait for the warmer months or run the backup GFA furnace and let the slab go cold and heat each zone up, checking with an infared therm or camera. Or just try to starve the line closest to the garage and test over a few days and pray for a good guess.

Thanks for the help, eager to hear more opinions to make me feel better.

RLuck

Check to see if you are taking advantage of the off peak billing if cost is your main problem. can't tell from the picture. If not using off peak your bill will be MUCH higher.

RLuck

Find out the electric peaking rules from the utility and run, program to take advantage.

Jamie Hall

Your best bet, as a start, is to let the slab go cold, and then run one loop at a time. You can use an IR thermometer or, better, an infrared camera, to show you where the loop pipes run -- they will show up surprisingly quickly with the camera, but the IR thermometer will do a decent job too. It won't take all that long.

Once you do that, you can begin throttling back the over enthusiastic zones.

As a general sort of thing, electricity is the most expensive way to heat a building (even on off peak), although there are a few exceptions -- you aren't in one of the exceptions. I'd get through this winter, and then plan on installing a mod/con LP boiler with proper piping and controls, including outdoor reset. You'll be happier. And wealthier...

HVACNUT

Are all the return pex lines returning hot? Can't tell by the pic if you have isolation valves on the pex loops. You should. What's the boiler limit set to?
Where is the thermostat located?

Electric boiler in Minnesota?
I've got a #6 oil boiler running my 1br. bungalow in Key West.
Definitely replace that boiler with LP or oil. Like Jamie Hall said, an LP low temp mod con boiler will probably pay for itself in no time. The colder it gets, the more you save.
Once you determine where the loops are going, you can change the manifolds, install actuators and zone it.
You said you have a backup gas furnace. Central? Do you even need the boiler?

rick in Alaska

Is the pressure in the boiler constant, and do you have the fill valve on all the time? I am wondering if maybe there is a leak in the slab. You can check this by turning off the feed valve and watching the pressure for a while to see if it drops.
$700 a month is a lot for a place where your electricity is only a dime per kw.. I would see if you can get hold of an infrared camera and take a look at your floor in various places to see if it looks balanced on output. Also, take an infrared thermometer and check the temperature on each one of the loops for supply and return temperatures. Since you say you do have valves on the manifold, although I don't see any in the picture, you can close some of them down to balance out each loop to get the heat where it needs to be.
Rick

DZoro

Get rid of the electric boiler- Install mod. gas
2 zone house/garage
Good thermostats slab sensing if you can find a spot for them
If you have perimeter insulation, the same is probably under you.
You will save money......a lot of it!

Gordy

From your house dimensions, and number of loops. We can assume the loop layout is 1' centers IF the installer knew what they were doing with normal installation practices for maximum loop lengths.

The garage is more than likley the bulk of the electric bill if kept at 80*. You need to zone the grarage from the rest of the system. Keep it 50 ish.

The farthest loops from the manifold suffer from temperature drop before the water gets to the far end of the house. Could be exceedingly long loops because of long leader lengths to get from far end of house to the boiler, and back.

Technically the loop lengths should be in manageable lengths of less than 300' with leaders. Problem being is if the loops are close to the same lengths.

whitt_travis

Thanks for all the help guys!

I know diddly about hydronic in floor so the information was helpful. I brought out a few contractors to take a peak at a few things, and probably the least of the worries was the floor heat.

We ended up walking away within our inspection period, nothing that wasn't fixable but not at the price point I came in at originally.

rick in Alaska

Thanks for letting us know the outcome.
Rick