Hydronic heat not as efficient as forced air ?

lucky

Without a reset installed, my other alternative is to manually turn down the space heating water temp on the boiler panel from 125 to some lower temp and see if that helps.

Gordy

Yes you can do that if you like to fiddle with it every time the outdoor temp swings. You could get by experimenting if the weekly temps are consistent. But that’s still not going to beat ODR. It’s constantly monitoring the outdoor temps, and adjusting supply water temps accordingly. Even from day to night you could have a outdoor temp swing that could change the supply water temp drastically.

lucky

Yes, I realize that without the reset I wont get that benefit but I am just wondering if there is some other temp I should reduce it to and leave it at, that may be better than 125 as the temp that is being used all of the time. That may improve efficiency some but obviously not as much as if the reset was there. I don't plan to fiddle with it all of the time just find a temp that works better than 125 and leave it there.

Gordy

Try 105-110

Gordy

Question:

You have flow meters on that pex manifold. What is the flow rate for each loop? Check while pump is circulating.

That boiler needs a minimum flow rate of 3 gallons per minute. Max 11 gallons per minute.

kcopp

The outdoor reset sensor is a simple 10K sensor that hooks up w a 2 wire thermostat wire. Not that hard to do....

KC_Jones

> @kcopp said:
> The outdoor reset sensor is a simple 10K sensor that hooks up w a 2 wire thermostat wire. Not that hard to do....

Apparently it is for many contractors. How many times have we seen it on here?

"More trouble than they are worth"
"They are only for big boilers"

Those are 2 that I can remember coming from other posters on this site when quoting their contractors.

SuperJ

My two cents on improving efficiency based on a quick review of the manual. http://www.ibcboiler.com/support/TIPortal/Content/Guides and manuals/DC_HC_ContManual_English_R1.pdf

Get you ODR reset working, but in the meantime bring your water temp down as low as you can.

Limit the heating power in the installer options. Combi boilers are usually way oversized for the space heating loads. You may be able to limit the boiler to 40% and still maintain your heating load. It's more efficient to run long cycles at lower modulations rates. Don't be afraid of long long cycles as long as your space is comfortable. There is no hurry with hydronic heat.

I think your boiler supports a system temp sensor that you can locate downstream of the closely spaced tees. This is a better sensor to control off of, especially if your secondary flow occasionally exceeds your primary flow.

Check your temp delta at max fire. You may be able to reduce the pump speed/throttle a balancing valve and still keep you delta below 30F. Over pumping the primary dilutes your return water with excess hot supply killing efficiency. On the flip side if you don't have enough flow that can hurt you too. Too little flow will result in an excessive temp delta (more the 30F).

Look into your DHW options. There settings to keep the HX warm this will burn more gas. There is a compromise mode called ECO mode where it maintains a DHW hx temp only during periods that it has learned you use DHW.

Gordy

Well I was leading up to this. The OP isn’t a seasoned hydronic guru. I’m quite sure this installer set everything up as to not get call backs for lack of space heating, or dhw output. So not the most efficient setup.

ChrisJ

I didn't see anyone mention it, but if you're going to use an IR thermometer you need to let it stablize at the temperature you're going to use it at. If you keep it in a 70 degree house and then bring it out into -20 air and try to use it you're going to have a bad time.

Gordy

Most of my suggested areas to take readings were along the wall/ floor intersection for the interior space.

Ironman

On ODR: Bosch said that they did a study and found that 77% of American contractors who install mod/cons did NOT connect the outdoor sensor or setup the reset curve. It lead them to develope their indoor reset 2 wire thermostat.

Unfortunately, this industry like most others, is plagued with incompetency and laziness.

It's indicative of society.

Solid_Fuel_Man

I couldn't agree more!

So many people who are in the trades have little idea of what actually is going on. It's sad, always keep learning, ask questions.

hot_rod

I think many hydronic installers struggle to keep up with work load and providing a living and do not make enough time to get educated on the latest technology.

Imagine knowing how to program and set up every mod con boiler control available today!

Getting the basic understanding of how ORD functions is a good first step, its applies to all controls.
tekmar always did a good job of teaching the theory first, find their training online.

Online training is making it easier and easier to stay current, we had 636 sign up for our last Caleffi webinar, it is how the industry "wants" to learn these days.

Ironman

Caleffi is doing an outstanding job of providing training to the trade. The sad thing seems to be that only a minority of people wanna learn.

I talked with a rep for a major manufacturer about this sometime back. He told me that at a national trade show they offered free technical and marketing seminars and about 93% percent of those that signed up did it for marketing. Too many wanna turn a buck but not offer in return the expertise that dollar is spent on.

Considering the amount of info that's now available through the net (like this extraordinary site), there's no excuse for not having adequate knowledge of the trade.

None of us knows it all, but that's why we are here to share and learn.

KC_Jones

And some don't want to learn. We have manufacturers training on our industrial equipment. This last round several were asked to never come back as they just sat there playing on their phones the whole time. Why did they come? We give slightly better commission for extra training. They wanted the money, but not the knowledge. Well now they get neither. The level of shortsightedness there is staggering.

Solid_Fuel_Man

There still seems to be the guys who hang 6 circulators on the return for a modestly sized new home, and put in fin tube.

hot_rod

I'm going to make the reach to any and all, the saying "you can lead a horse to water, but you can't make them drink".

Age does not matter or seem to have an effect on willingness to keep learning and expanding knowledge base.

If they get hungry enough, their motivation tends to changes

lucky

As someone mentioned above, this is my first house with hydronic heating, I am not an HVAC person and I know nothing about it. I am very thankful to be learning from all of you, again thanks for all of your comments and suggestions, I have learned a lot from you over the last few days.

Gordy

lucky said:

As someone mentioned above, this is my first house with hydronic heating, I am not an HVAC person and I know nothing about it. I am very thankful to be learning from all of you, again thanks for all of your comments and suggestions, I have learned a lot from you over the last few days.

Read the manual. Especially the control manual. Just like any appliance.

Any question, or something you don’t understand just come back.

Hooking up the ODR sensor is as simple as mounting the sensor running the wire, and hooking it to the proper terminals. Check the ohms.

Gordy

hot rod_7 said:

I'm going to make the reach to any and all, the saying "you can lead a horse to water, but you can't make them drink".

Age does not matter or seem to have an effect on willingness to keep learning and expanding knowledge base.

If they get hungry enough, their motivation tends to changes

I think there is a mix of why some installers don’t install the full benefit of ODR function.

Lack of understanding of how it works.

HE Boiler installed on high temp radiation that they assume needs full output to heat the structure all season long. See first reason.


Possibly call backs from previous times they did install it because of improper set up, or owner fiddling with it, and call backs. See first reason.


Worried about call backs because house isn’t heating with an aggressive reset curve. See first reason.

lucky

As an update, I received the IR temp gun today that I had ordered and measured the outside temps of the cement blocks around the outside of the slab. The outdoor temperature was 42 today but had been in the 20 's the last few days. The cement blocks around the slab measured about 36, colder than the current temp because they were probably cooled down by the 20 degree temps over the last few days. But in any case they were not warmer than the current temp so I assume that would indicate that there is perimeter insulation around the slab which is one of the questions that several of you had asked about.

Gordy

You want to take reading on the “inside”of the house where the exterior wall sits on the slab. This will give a good indication if the interior slab is conducting the cold to the slab.

However your readings do indicate the block is not sucking heat from the slab. Is the radiant running?

Leon82

> @lucky said:
> As an update, I received the IR temp gun today that I had ordered and measured the outside temps of the cement blocks around the outside of the slab. The outdoor temperature was 42 today but had been in the 20 's the last few days. The cement blocks around the slab measured about 36, colder than the current temp because they were probably cooled down by the 20 degree temps over the last few days. But in any case they were not warmer than the current temp so I assume that would indicate that there is perimeter insulation around the slab which is one of the questions that several of you had asked about.

I have been told that an uninsulated basement can account for up to 10k btu of heat loss at approx 3 feet of exposed blocks

lucky

The boiler is not currently running, it normally runs about once per day and then the floor radiates sufficient heat for almost 24 hours before it runs again

Gordy

^ for any size basement?

Gordy

lucky said:

The boiler is not currently running, it normally runs about once per day and then the floor radiates sufficient heat for almost 24 hours before it runs again

Interesting. How long does it run when it does?

lucky

The boiler generally runs for 2 to 3 hours once it starts before the floor is generating enough heat to get the thermostat above the set point.

Leon82

> @Gordy said:
> ^ for any size basement?

I am not sure I had asked on another forum . Mine is approx 1400 sq ft

Gordy

@lucky does it cycle (meaning on and off) in that time frame it is running? Or does it modulate to keep the fire always going.

Gordy

IF the boiler is running at full input 125k for the 3 hour time frame that’s 3.75 therms a day if you are on NG. I’m going to assume the boiler is modulating in that 3hour time frame. So the 3.75therms a day is a high estimate.

lucky

I am not sure, I have not watched the boiler itself the whole time it is on, I have monitored the thermostat to see how long it is reading "Heat on". If the thermostat is reading "Heat on", does that mean the boiler is currently firing or could the boiler be cycling on and off even though the thermostat is calling for heat the whole time ?

Gordy

I don’t know what your NG costs are after all fees per therm.

How long did the forced air furnace run a day when you were just using that? How many btu input is it?

Leon82

Heat on means the t stat is calling for heat. The boiler can be off during this time if the set point is met.

Gordy

lucky said:

I am not sure, I have not watched the boiler itself the whole time it is on, I have monitored the thermostat to see how long it is reading "Heat on". If the thermostat is reading "Heat on", does that mean the boiler is currently firing or could the boiler be cycling on and off even though the thermostat is calling for heat the whole time ?

No the thermostat calling is no indication of the boiler cycling, or not. It is an indication the house needs btus to reach setpoint.

That’s a long heat call to reach setpoint in one part of a day. Once that slab, and house are at set point it should just need a bump now, and then.

You are not using set back so are you?

lucky

The furnace would cycle on and off several times each day for several minutes each time it was on. I don't know the BTU's of the furnace, I have read all of the printing on the furnace but can not find the BTU output. I assume it is probably around 80K BTU. The cost in my area is about $.90 per therm used including fees and BTU multipliers etc.

lucky

No we are not using set back, the thermostat is set at a constant 68, once the floor is heated up and the boiler shuts off, the temp in the house generally continues to rise to 70 and then stays at 70 for about 18 hours before it starts to fall back to 68 and the cycle starts again.

neilc

i think it's been said here but you have to dial that OA reset down 5, 10 , 15 * over the next 3 weeks till you find the room doesn't quite keep up, then fine tune it a degree or 2 at either the high end, or the low end, depending on the OAtemp, at the time.
If it's warm out, and the room is keeping setpoint, try to dial down the top end.
If it's cold out, design temp like, and the room starts getting behind, add a couple degree to the low end.
You could tweak this all winter.

lucky

As I mentioned way back at the beginning of this thread, during the summer we consistently use about .5 therm per day for all natural gas appliances so space heating is on top of that. When I conducted the test we used 2 therms per day when the forced air furnace was running and 3.5 therms per day when the boiler was providing the space heating. If you subtract the .5 therms for the other gas appliances, that left 1.5 therm used per day by the furnace and 3 therms per day when the boiler was providing space heating.

lucky

Yes, I moved the supply temp down by 5 degrees from 125 to 120 and am testing that now and will continue to tweak until I get the most efficient setting.