Replacement of old oil boiler running Hydroair. - System2000 question.

Steve71

Hi. Need some help please. Current WTGO-5 boiler is very old and runs Weil-McLain 80 gallon indirect tank. Boiler Net rating is 155,00 BTUs/Hr. House is 1957 2300 sq feet ranch in Connecticut. Anticipating a boiler change in the spring and considering S2000 from EK, Current set up is working great for hot water. Heating is adequate at best. No leaks or major issues with current boiler, but want to have a plan in case it fails. Current boiler is well maintained. Moved into this house 5 years ago and installed Hydroair and A/C. ADP product is located in uninsulated attic. Ripped out water baseboard heat (which was probably a mistake). House sits on uninsulated crawlspace. All windows are new and I have been air sealing cracks and opening around foundation/sill as much as possible. Insulation in walls is unknown,

Current situation: Heat load analysis using online tool shows need 125,000 BTUs/Hr. (I put in all the info. for room dimensions, window sizes, door sizes, etc.) ADP coil is 4 rows and fixed fan speed on medium is1500 CFM. Coil is rated at 98,851 BTUs at 4GPM. 105,000 BTUs at 5 GPM for water temp of 180 degrees. - Maximum input temperature to the coil cannot be greater than 180 degrees. This is why I set the limit on the boiler to 175

Taco Pump sits on return loop to boiler and is 007-f5-7IFC. I'm assuming the 007 manes 7 GPM but am not sure. Head is not known,

Boiler has new expansion tank, new Honewell Aquastat, new aquastat for indirect tank, new controller for Beckett burner. Water is hard and contains a lot of iron. - Water is untreated going into the boiler. House water has a water softener and a separate filter for Iron,

House is 4 bedrooms 2.5 baths. Two people live here, but want to size everything correctly for a family of 4-5;

Attempted to measure return water temp and outgoing water temp using multi-meter temperature setting, but don't trust the results. return temp is 130 degrees (measured close to the boiler return); Supply temp; maxes out at 150 degrees once boiler reaches high limit of 175. After burner shuts off at 175 degrees, boiler temp goes up to 182.

Questions::
1. Is System2000 a good fit for my situation with Hydroair? Other options? Burderus? - I would consider a mod/condensing boiler but don't think this setup is the right match for high temperature Hydroair and am concerned about finding somebody who can install it correctly. - Looks like there are System2000/EK installers in my area.
2. Is the Taco 007-f5-7IFC the correct pump size or how do I determine if it is?
3. Why does supply temp measured right before the water goes into the PEX line only 150 degrees when the boiler temp is at 175? (I measured on the copper before it hits the PEX. Looks like a one inch diameter line or maybe a little larger). - Again, I measured using a multi-meter temperature wire, but not sure how accurate it is. Is there a better way to measure this? The strap-on thermostats don't seem too accurate either.
4. Would it be better to put a variable speed ECM motor in the Hydroair unit to vary the CFMs? (This unit has an option for ECM variable; Not sure how it would be controlled.)
5. Since Hydroair coil is undersized compared to heat load, I could put baseboard back in one of the rooms (350 sq feet) that is furthest from the boiler and is always colder than the other rooms due to the quantity of windows. This one room has a heat load of 20,000 BTUs/hr. Have space for 16 feet of baseboard.
6. I have read on this forum where other people run Hydroair at 140 degrees and get good results. My setup would probably be too cold at 140. What do I need to change?
7. What else should I be taking into account?
8. Note - I intend to have the HVAC company re-do the heat load analysis or will hire somebody to do it. This is the first time I have used the tool, so want to make sure I am doing it correctly.

Sorry for the long post but have read many posts on this forum and seems like best to provide as much info. as possible.

Thank you very much for any ideas, observations, and suggestions. I'm impressed by the quality of information shared on this forum.

Jamie Hall

If your heat load analysis is correct... and the coil rating is correct... you are short about 20% of your heating load. Changing the boiler will not fix that -- it doesn't matter a bit what size the boiler -- if you can't get the heat into the space, you can't get the heat into the space.

EBEBRATT-Ed

I would have left the baseboard or add it back in if you can. It will heat much better especially if your duct supplies are in the ceiling

Steve71

Thanks.  Will plan to add back in at least some of the baseboard. This will shift about 20,000 BTUH from the Hydroair coil to baseboard and will help.

KC_Jones

The heat load seems way high unless this is a glass house, with the doors open. I am speculating you don't have that given your description of a 1950's ranch. 54 btu/sqft is higher than my 100+ year old house with essentially no insulation except attic, and original wood windows.

The boiler you have now is technically oversized because of the output of the rest of the system, so as said anything bigger does nothing.

I would suggest revisiting the heat load numbers before moving forward. If the load is lower (I suspect it is), to me that would indicate you are not getting the rated output of the coils, or the output is not all going into the house. Could be a duct work design issue.

You mention the ductwork in the attic, was the duct work insulated? You also say the attic isn't insulated, do you mean there is zero insulation anywhere, or that the ductwork is above the insulation? If you have zero insulation in the attic I would make that a #1 priority before doing anything else. That is a huge heat loss area.

EdTheHeaterMan

Steve71 said:

Thanks.  Will plan to add back in at least some of the baseboard. This will shift about 20,000 BTUH from the Hydroair coil to baseboard and will help.

Only if you close off the duct to the 20,000 BTU room. If you don't do that you will still be sending the unneeded BTUs to that room, and the other rooms will not have the benefit of that heat.

Roger

Thank you for your post, @Steve71 , and for everyone's replies.
System 2000 has been used with great results for decades on thousands of hydro air installations. Hydro air should be installed with a zone valve with an endswitch or a holding relay so the air handler fan will continue to run during thermal purge. We have seen additional energy savings of 20% when this was inadvertently not done, and then corrected later. For hydro air, you will see a fairly small heat output change with the hydronic flow rate, so varying an ECM circulator will not be worthwhile. System 2000 does come standard with an ECM circulator, so it will run with low power consumption already.
I believe you will find that baseboard will be quieter, more comfortable, and more efficient as it does not have duct losses, but you will have to do what you decide is right for your home and your heating and cooling needs.
If the burner on your existing boiler is turning off when there is an active thermostat call for heating zones that heat inadequately, that means that you do not have enough radiation (or air handler capacity) for that zone. If the burner never turns off, then you are limited by boiler capacity as it cannot catch up.
What is your annual oil consumption? This will give you a real world idea of what your heat loss is now, although it sounds like you intend to add radiation to make your house warmer which will increase your design day load. In general, design day is about 1% of annual usage due to degree day analysis, so annual use is about the following BTUs/hr = GALLONS x 0.01 / 24 hours per day x 138,600 BTU/gallon. A 1000 gallon example is 1000 x 0.01 / 24 x 138,600 = 57,750 BTU/hr on design day. This of course does not tell you how much radiation you need in each room, or how much energy is lost through ducts in unheated spaces.
Best,
Roger

Steve71

Thank you Roger. - I am going to add some baseboard which will help. Will also do the calculation for design day based on oil usage.

Steve71

Thanks KC. Agree that my heat load calculation seems way high. The house is not large and has new windows. I am going to get somebody to run the heat load for me and I'm going to re-check my #s. The ductwork is insulated. Flex ducts with R6 or R8. The main ducts feeding the flex are also insulated. The attic floor is insulated with standard rolls of insulation and 2/3 of the attic floor is covered in plywood flooring. I spray foamed around all penetrations. The roof area and gables are not insulated.

Steve71

Thanks Ed. Yes, will close off the duct to the 20,00 BTU room. This was a porch/3-seasons room converted to an inside room. May consider a single zone mini-split for this room or put back in the baseboard.