hydrostat 3250 and my new boiler

TerrS

Hi,

 I'm back with yet another new issue. In reading this issue from Mike, I have the same exact issue https://forum.heatinghelp.com/discussion/186531/hydrostat-3250-plus-a-simple-intelligent-solution-needed

I have talked to Mike at hydrostat 4 times already about my system setup. He has been amazing but I think I hit a technical limit of the hydrostat control.

And this is because of the way the termal boost works, only increasing the setpoint temperature every 30 minutes, which is FOREVER. I might remove my ODR, because without an ODR attached there are like 6 economy levels you can set. Lo increases boiler temperature every 10 minutes, 1 every 15 minutes, 2, every 20 minutes and so on. So without the ODR the house heated up from a 3 degree nightly setback in about 45 minutes to 1 hour. Getting my water to 185 degrees. Currently it takes 2+ hours because of that 30 minutes of waiting to increase yet thermostat is still calling for heat.

Has anyone found a way to override that timeframe? I like all the features and energy saving of economy but there is a lot to be said about heating water starting at145 to finally 185 degrees over 2 hours and firing the boiler a dozen times, compared to maybe 4 times quickly heating the water and satisfying the t-stat quicker.

Otherwise I think the ODR is useless in my house!!!

Thanks Terri

neilc

you kinda have to decide between running ODR and realizing the economies in ODR, and doing setbacks and thinking there's an economic return there, (or is the setback for cooler sleeping temps?)

TerrS

neilc said:

you kinda have to decide between running ODR and realizing the economies in ODR, and doing setbacks and thinking there's an economic return there, (or is the setback for cooler sleeping temps?)

Yes can't sleep in a hot house, it goes from 68 to 65 at night. I like everything about the ODR, except the 30 minutes for the thermal boost to kick in. I am already at 2.50 ratio reset. If my house had high efficiency radiators instead of generation 1 Fins it would probably be great. But at 600btu per foot at 180 degree water my house heats perfectly fine. Not so much between 145-170 degree water. Just not enough radiation.

neilc

there's another thread here where someone was looking to install a ODR/Preset switch, like you're describing,
tie that in with a 24 hour clock, and some tender internal electronic bypassing,
you've got me thinking of a retirement plan right now

109A_5

Hello @TerrS,
If you want to experiment with the system. You could get a fixed resistor that represents a significantly colder outdoor temperature, say 15 degrees Fahrenheit, and when you want the fast recovery from a set back, switch in (just for the recovery time) the fixed resistor to be a substitute for the outdoor sensor, instantly its very cold out, different part of the ODR curve.

It may do what you want and maybe you can get the best of both worlds or it may just drive the ODR algorithm nuts and have unforeseen results. Resistors and switches are inexpensive. You just have to determine the correct value of the resistor, the ODR sensor is probably just a NTC Thermistor.


https://s3.amazonaws.com/s3.supplyhouse.com/product_files/Hydrolevel-48-140-Install.pdf

Since Hydrolevel does not seem real forthcoming with a resistance vs. temperature chart of their outdoor sensor maybe a 100K (100,000 Ohm) potentiometer (a variable resistor) and use the Hydrostat 3250's display would be simpler.

ethicalpaul

Can’t you start the recovery earlier?

TerrS

ethicalpaul said:

Can’t you start the recovery earlier?

Yes but that burns the same amount of fuel, because it takes 2+ hours to get the water to the temperature I need.  I really want the thermal boost to react quicker.

TerrS

Thanks everyone. I broke down and called hydrostat again and talked with Mike.  He stated the current design doesn't allow for a thermal boost time change which is hard coded for 30 minutes. He did however take a customer request to externalize that thermal boost to a customer setting like 10, 15, 20 or 30 minutes.

So I had to pull the connectors off the ODR. Hey maybe they will fix their design issue in the future.......

ethicalpaul

TerrS said:

ethicalpaul said:

Can’t you start the recovery earlier?

Yes but that burns the same amount of fuel, because it takes 2+ hours to get the water to the temperature I need.  I really want the thermal boost to react quicker.

I’m confused. You are going to use the same fuel to recover from a setback regardless. Is there some free heat you get from a fast recovery?

neilc

TerrS said:

So I had to pull the connectors off the ODR.

that actually makes my timeclock idea easier,
have the clock make or break the ODR at say 6am - 9am, then run the ODR rest of the day,

truth is though, your still burning the same gas doing that come back from set back, guess you can be eco the other 20 hrs of a day

@EdTheHeaterMan could draw you a nice diagram,
or @109A_5 as he's here already,

TerrS

ethicalpaul said:

I’m confused. You are going to use the same fuel to recover from a setback regardless. Is there some free heat you get from a fast recovery?

Actually that is not true, my new boiler heats water very quickly. Meaning with 1 zone calling for heat the water temperature will go from 110 degrees to 185 in around 10 minutes. Then using the thermal purge setting I can raise the house temperature those 3 degrees in less than 1 hour. And the boiler only fires a few times.

What is happening now is boiler calculated setpoint  is 145, in 6 minutes it's at temperature and boiler shuts off, pumps circulation water. Water temperature drops 15 degrees and because T-Stat is still not satisfied, boiler fires again and again for 2+ hour, because thermal boost setting will only raise setpoint every 30 minutes. With ODR removed I set economy to LO, which means every 10 minutes the T-stat is still calling for heat it will raise the setpoint by 10 degrees. So starting at the 145 initial setpoint it only take 30 minutes or so to get to the high limit. And my Fins radiate 580 btus at 180 degree water.

GGross

It is still going to take the same amount of energy to raise the temperature 3 degrees whether it happens in 10 minutes or 2 hours, unless the burner is running more efficiently in one of the 2 circumstances the same amount of fuel will be used. Personally I would say if this is a cast iron boiler I would just disable the ODR, in either scenario the question to ask yourself is "is a perceived or actual fuel savings worth my comfort" and I believe the answer in this case is no

ChrisJ

I'm using steam, but I'm sure there's similar options for hot water.

I keep my house the same temperature all day long. Bedrooms 64-66. Bathrooms run about 74, kitchen 68, livingroom etc 72.

My reasoning? I pay to be comfortable. The cheapest temperature is just to turn the system off, that's really cheap to run. If I'm going to pay to run it I might as well be comfortable all of the time.

I like the bedrooms cool and I keep them that way, all of the time. If someone doesn't like their bedroom that cool they can turn up the TRV and overtime it'll gain temperature and stabilize where they want it.

Bathrooms are warm because a cold toilet sucks. People are also in there partially dressed etc, so it should be toasty and comfortable. Also helps with humidity issues from showers.

I tried using setbacks to sleep comfortably because I can't sleep in a warm room and just gave up because it also meant cold toilets, cold kitchen etc. Setbacks are the wrong tool for this in my opinion.

All of that said......
I agree with others, you're not saving anything. I'd argue that running water 180F is costing you because it can't be condensing at those temperatures. Faster is never cheaper.

TerrS

@GGross

Actually I have watched the house heat quicker without the ODR attached. What I was hoping the ODR would have done was if it's really cold, I was hoping it would raise the boiler temperature quicker but it doesn't because of thermal boost 30 minute time delay.

.

If I fire my boiler for 15 minutes, the water is now 185 degrees it then uses thermal purge to drop to 170ish then will fire again. And remember now my Fins are giving off way more heat, between 500-600 BTUs per ft, not 350 at 145 degree water. So boiler not have to run long to raise that water back to 185. So in 1 hour I am warm and the boiler might have fired 4-5 times in that hour.

With ODR, Now it keeps heating the water to only 145 for 30 minutes, then thermal boost says nope T-stat not satisfied raise setpoint to 155. Rinse and repeat for 2+ hours which uses way more fuel.

EdTheHeaterMan

Are you looking for comfort or economy? Select one. Comfort costs more. Burner operation is a matter of mathematics and physics. The amount of heat needed to raise the temperature of a pound of water one degree is one BTU. That will not change based on the time of day or if the building is occupied or unoccupied.

The way that heat passes through a structure is measured in something we call the U-value. U-Value is the rate of heat flow in Btu/h through a one square foot area when one side is 1°F warmer.


Basically, you will have a lower energy bill if the difference between inside and outside is lower. So when you lower the indoor temperature (the part you can control) as the outdoor temperature drops (the part you can't control) the energy usage will be lower. If you raise the indoor temperature, you will be more comfortable, but you will use more energy.

Now if you change from 60°F desired indoor temperature to 65°F desired indoor temperature, the energy savings for the last 4 hours will be used up in recovery. So the lower indoor temperature needs to be lower for more than 4 hours for the set back to be considered a savings. Otherwise you may as well just leave the thermostat set at 65°F.

Think of it like this: You can operate the burner for 60 minutes every 4 hours. The indoor temperature will drop to 60°F by the end of the 4 hour period. Then the burner will bring the home back to 70°F at the end of the cycle. The average temperature is 65° BUT YOUR COMFORT WILL SUFFER.

You can operate the burner for 5 minutes every 20 minutes and use the same amount of fuel. Your comfort will be much better.

Now this is an oversimplification because it does not take into consideration the inefficiency of short cycles and the down time loss of keeping the heater at a higher temperature every 20 minutes, but the concept is easier to understand if taken one piece at a time.

So a setback is only effective in cases where the setback can be for more than 4 hours, and if comfort is sacrificed, is the saving really worth it? Then of course there is the impression of savings whether actual or perceived, based on how your mind sees the operation of your heater. If you believe that you are saving (even if you are not) then you will be more comfortable having this feature and I would be happy to assist you in designing a device that will accomplish what you want.

TerrS

@ChrisJ completely agree and will never install a condensing modulation boiler in my house. Cira 1903 vintage updated to hot water probably in 1940 or 50's. My new cast iron Dunkirk 101k BTU output with now 4  independent zones, now heats my house perfectly given 180 degree water. The issue is how fast I heat the water to that temperature on cold days.

GGross

TerrS said:

@GGross

Actually I have watched the house heat quicker without the ODR attached. What I was hoping the ODR would have done was if it's really cold, I was hoping it would raise the boiler temperature quicker but it doesn't because of thermal boost 30 minute time delay.

.

If I fire my boiler for 15 minutes, the water is now 185 degrees it then uses thermal purge to drop to 170ish then will fire again. And remember now my Fins are giving off way more heat, between 500-600 BTUs per ft, not 350 at 145 degree water. So boiler not have to run long to raise that water back to 185. So in 1 hour I am warm and the boiler might have fired 4-5 times in that hour.

With ODR, Now it keeps heating the water to only 145 for 30 minutes, then thermal boost says nope T-stat not satisfied raise setpoint to 155. Rinse and repeat for 2+ hours which uses way more fuel.

My suggestion was to disable the ODR so that you could recover the setback faster. You are still using the same amount of energy to raise the temperature those 3 degrees though, the boiler is not firing 100% of the time while it is on ODR

TerrS

@EdTheHeaterMan

 So just for perspective, 5am thermostat says warm house to 68 degrees. Everyone wakes up at 6am and leaves house. At 8am, setback to 64 degrees.  At 3pm raise back to 68, and finally at 10pm back to 64.  So 16 hours a day the house is 64 degrees. For the other 8 around 68 degrees.

I am not trying to disagree with the experts that do this for a living every day, but I have lived in this house 32 years and watched what it takes to heat it. And your right, I do compromise economy and comfort at certain times.

GGross

I think everyone agrees with you that you should do what you need to be comfortable. The only disagreement is in how much fuel or energy is used to raise the temperature from a setback, and unless the burner efficiency changes it will be the same no matter how long the recovery takes. The same amount of BTU will be required to raise that temp, whether it is delivered over a 2 hour period, or a 10 minute period. Of course over the course of that 2 hours there is additional heat loss, but that will be there no matter what

TerrS

@GGross

 I really want to understand how you calculate it will take the same amount of energy to raise house temperature by 3 degrees?

If you continually heat water to only 145 degrees, given fins only give off around 350btus per foot at that temperature, you do that for 30 minutes, then it raises to 155 for 30 minutes and etc, the boiler is firing many many more times but will never satisfy the heat demand.

So spending the extra 5 minutes of boiler firing to heat the water an extra 40 degrees, not only increases the radiant heat given off from the Fins. But with thermal purge waiting until 170 to refire boiler I am still getting 500btus per ft. This causes not only the demand to be satisfied quicker, the boiler after the first initial fire, only has to run 5 minutes to reheat water back.

GGross

Lets say for example you will need exactly 10 units of energy to raise the temperature in a given space by 3 degrees. for example lets say I have 2 delivery methods, the first one instantly delivers those 10 units of energy to the space, raising the temperature and satisfying my needs, the second method delivers 1 unit of energy every minute, it runs a cycle for 10 minutes and raises the temperature satisfying my needs.

So delivery method 1 ran for less than a minute, delivering 10 units of energy

delivery method 2 ran for 10 minutes, delivering 10 units of energy

which deliver method used more energy?

ethicalpaul

You lose more money by heating it fast also because of the greater temperature differential over more time. But it’s pennies

TerrS

@GGross

So in your example I would agree both used 10 units and the same cost hypothetically. But here is where I disagree with that not being equal or correct to heat the house.

The elements providing that heat only give off so many BTU's at a certain water temperature. So I will not say the energy at 145 water is totally wasted, but it didn't raise the house temperature. Even at 155 and 165 until the water gets to 175 degrees does it start really start rising the house temperature. Given that was 1.5hours of wasted energy with no increase to T-stat setting, in my mind used excess fuel.

GGross

Well rest assured that I think your plan to recover faster is in fact the correct thing to do! But it will take the same amount of energy to raise the temperature assuming the burner and emitters etc remain the same. You must remember that in the real world that is your house you are also dealing with latent heat loss, which is present in either scenario, you will still use that energy to maintain the temperature once it is raised, delivering more BTU/hr will just get you there more quickly

TerrS

@GGross

I agree removing the ODR unless hydrostat fixes what I consider a design flaw will fix my issue. I will also agree with heat loss present, but at 145 degree water it's not enough to overcome. At 175 and above it will overcome and satisfy.

Thank you

EdTheHeaterMan

So now we are back to the perception issue. It is perceived that the recovery must start only moments before the desired temperature is required. If that perception is changed to allowing the control to get there in 2 hours so just start the process 110 minutes earlier, then the problem is solved. The perception is that starting 110 minutes earlier is somehow inefficient. This is not exactly true. There is the issue that in milder temperatures the time frame may be less than 2 hours and during severe weather it may take longer. So adjusting the clock may only offer limited success.

TerrS

@EdTheHeaterMan

Ed it's really not perception at all.. for 30 years I know you took 1 hour to heat my house up from that 4 degree setback and felt yes I was saving Money as there was an 8 hour timeframe between 68 when people are home or when away or sleeping.

However since I hooked up the ODR, that time went to 2+ hours, so I knew something was not quite right. And that was the amount of radiation from 145 water to the amount at 180 degree water.

Now on warmer days I will still see some benefits of the economy setting as the t-stat will be satisfied with 165 or so water. But on colder days it will only take 30-45 minutes for the boiler to get to 180 degree water to heat my house.

Lastly for the past month I have been tracking CFM used on my gas meter. So next month since I have now removed the ODR I will compare to see, but also comparing outside temperature between December and January

EdTheHeaterMan

I may have misspoke. Perhaps perception is the incorrect term. The new normal is 2 hours based on energy saving technology. The fact that it warmed up in less time is based on the fact that there was a longer burn time in the past. The longer burn time allowed the water temperature to reach 175 within a few minutes. The new normal has a series of short burn times over 2 hours. Since you may hear the burner come on several times over that two hour period, it appears that the flame is on longer, but if you actually timed the flame on over 2 hours with the new control, and compare it to old one shot long burn time within 30 minutes, there will be very little difference in burn time. That is because 8 or 9 short burn times feels like more fuel is being used because you hear more starts. But do you hear the offs?

However I agree with you on how it should work. And I have a fix. There is a way to make that happen using a two stage heating thermostat. Usually used on heat pumps to bring on the electric resistance heat when the lower temperature heat pump compressor warm air is not enough to get the house comfortable. We can employ the same concept. When you turn your thermostat back to a higher temperature, the difference between the room temperature and the desired (or setpoint) temperature will be greater than the 1°F difference required for the second stage thermostat to call for auxiliary heat. (W2)

By adding a simple relay to the second stage heat (W2) the contacts on that additional relay can connect the ZC and ZR on the Hydrostat 3250 and fool it into DHW mode, allowing the high temperature limit to take control getting the boiler water up to the desired temperature immediately upon a call for set forward to the warmer home. This will drop out when the room temperature gets close to the set point and the W2 stage drops out, automatically reverting to the ODR function that you really want to keep operational for the most economical operation.


I would need to know more about your system to come up with a plan for your home, however here is one idea I have come up with that will work if you have only one zone of heating. The attached file allows for a thermostat that requires a common if you wish to use a WiFi compatible thermostat.

EdTheHeaterMan

Lastly for the past month I have been tracking CFM used on my gas meter. So next month since I have now removed the ODR I will compare to see, but also comparing outside temperature between December and January

I don't think you will see a great difference since all these different savings protocols save a small percentage. The first energy saving change makes the most difference. For example if you have a 1000 unit usage and you add something that will save 15% you will drop your usage by 150 units. The next energy saving item may also save 15% but you have a new starting point, 8500, so that will only reduce your units by 127 units. I don’t know why I’m telling you this, the law of diminishing return is understood by many and I would expect you to be part of that many, based on your conversions herein. Since you have employed several energy reducing protocols at this point, I believe that using ODR in November and not using ODR in December you will not see the big difference that you would in the fringe months like September and March where ODR has the best results.

If you are interested in a control design that will allow the ODR and also use the second stage thermostat to engage the higher temperature automatically, I would be happy to design something easy to implement based on your existing system. I would need to know all the controls that you have existing from the thermostat model numbers, to the zone controls, if any, and the number of heating zones, number of circulators, number of zone valves, and if you have a DHW zone or not.

Also if you have more than one heating zone, which heating zone takes longer to heat up based on the previous high temperature design. I will employ the two stage thermostat design on that zone because the other zones will already be up to temperature by the time the longest zone catches up to ORD operation.

Let me know if I can help in any way.

109A_5

Hello @TerrS,

neilc said:

TerrS said:

So I had to pull the connectors off the ODR.

that actually makes my timeclock idea easier,
have the clock make or break the ODR at say 6am - 9am, then run the ODR rest of the day,

truth is though, your still burning the same gas doing that come back from set back, guess you can be eco the other 20 hrs of a day

@EdTheHeaterMan could draw you a nice diagram,
or @109A_5 as he's here already,

If disconnecting the ODR sensor is the only thing you need to do to disable the ODR and reconnecting it enables it again without any ill effects, As @neilc said and similar to @EdTheHeaterMan's diagram, I would just use a Programmable Thermostat to control a relay (for isolation) to connect and disconnect the ODR sensor. The Programmable Thermostat and relay could be with the boiler since you are not really using the temperature part just the Day / Week timer part.

Any timer that has the timing capability you need will work. If it has isolated contacts you don't need the extra relay. A Programmable Thermostat may be simpler to deal with.

TerrS

@EdTheHeaterMan

First Thank you!! This might be a longer post...

I wish I had your expertise because I now agree I could possibly use the DHW circuit to accomplish what I need or would like.

So just a a refresher as you have commented on my previous posts. My 32 year old 150k input boiler with only 1 zone was taking forever to heat all the water to temperature even with the old Beckett aquastat. But that boiler at best was  only 75% efficient. Knowing I needed 175 or greater water temperatures to heat my house I replaced with a 30k input less boiler and efficiency of 85% now. 4 burners not 5.

So telling the whole truth, I separated that 1 zone into 4 so I could heat the house areas I was concerned about. Namely the attic so the pipes wouldn't freeze, so that's kept at 47 degrees. And bedrooms at 68 or 65 at night. The rest of the house is 64 or 68 depending on the area. Like basement and living room.

So far even with the issues I think I am saving 65 CFM at least for December but it was 8 degrees warmer this year than 2022. 

So it use to take 45 minutes to boil the ocean if 4 pipes on 1 zone needs heat.  Now happens in 15 minutes even if 1-2 or 3 zones call for heat. So keeping my house bedrooms warmer at night 65 compared to 64, has not cost me any extra money.

Like I said there is a ton of expertise here, I am just an informed homeowner that did a lot of reading on controls and paid attention to my heating cycles. I do mainframe computers for Banks for a living but I believe knowledge means you can make informed decisions to at least ask questions. If it becomes to technical without a diagram you will lose me.

Lastly my certified Dunkirk installer did my whole setup for a VERY VERY reasonable price with the 4 zones. Like Very reasonable, or some would call cheap. But he didn't setup any advanced options. I found things by reading the manual and calling hydrostat directly.

Again thank you!!

TerrS

@109A_5

 Yes and no. It's a 2 second hook up and disconnect but I lose 2 settings.  One being reset ratio and warm weather shutoff settings with ODR attached.

Going backwards I lose my economy setting of LO which resets setpoint every 10 minutes. Everything else stays.

109A_5

Hello @TerrS,

Well as I touched upon before maybe just use a resistor and a timer (Programmable Thermostat & a relay) to change the ODR curve just during the recovery time. Make the Hydrostat 3250 think it is -40 outside for an hour or so.

EdTheHeaterMan

Terri, When you say you have 4 zones, how are they separated? Are you using 4 zone valves?

When you separated the zones, did you use PEX home runs from each baseboard loop, back to the boiler room?

Another way is to have all the returns (or supplies) connected to the boiler using the old piping but make a separate supply (or return) with a zone valve on each branch, starting at a manifold near the boiler

Are there 4 separate thermostats for these zones?

OR

Are you just calling each branch of the baseboard a ZONE with one central thermostat that operates all the branches at once?

TerrS

@EdTheHeaterMan

So my old system had 4 zones or pipes as I will refer. Attic, 2nd floor bedrooms l, then front of first floor and rear of first floor plus basement.

He installed 4 zone valves on a 4 zone Honeywell control board. Then I installed 3 new thermostats adding to the one I already had. So 4 in total to match my already installed pipes/zones.

TerrS

@EdTheHeaterMan. I tried to attach pictures but it is not working for me

EdTheHeaterMan

So with this information you have provided, this is the best guess diagram for your installer or service tech. I attached the new thermostat to zone 4 but you will need to select the best zone based on how your system is wired. I might guess that you should use the first floor main living space at the override zone for this set up. You will need to purchase the 2 heat capable thermostat, and the RIB relay. You should already own everything else. A Spare transformer might also be in order. If the 40 VA in the Honeywell HPZC104 fails, replace it with a 50 VA.

This will make your system do what you want automatically without disconnecting the ODR wires. here is the parts list:
RELAY https://www.supplyhouse.com/Functional-Devices-RIBU1C-Enclosed-Pilot-Relay-10-Amp-SPDT-w-10-30-Vac-DC-120-Vac-Coil
Standard (2 heat) thermostat https://www.supplyhouse.com/Honeywell-Home-TH6220U2000-T6-Pro-Programmable-Thermostat-2H-1C-Heat-Pump-2H-2C-Conventional
Optional WiFi thermostat:https://www.supplyhouse.com/Honeywell-Home-Resideo-TH6220WF2006-T6-Pro-Smart-Wi-Fi-Programmable-Thermostat-2H-2C
Optional transformer in case the 40 VA fails. https://www.supplyhouse.com/Uponor-Wirsbo-A3050050-50-VA-Transformer.

If your installer or technician has any Questions I will PM you my phone number. Text before you call because my phone only rings for Known numbers in my contact list.

TerrS

20230907_150246

EdTheHeaterMan

I'm thinking this might be a wireless thermostat, but I can't be sure because the numbers are to blurry.

Otherwise my diagram for your system still looks correct.

dko

EdTheHeaterMan said:

the numbers are to blurry.

I was able derive at THM5320R with my squinting skills

TerrS

@EdTheHeaterMan

 Correct I didn't feel like running wire to my attic. So I did the red link setup. Otherwise I ran wire and installed 3 brand new

Honeywell Home RTH7600D 7-Day Programmable Touchscreen Thermostat