HTP UFT Tankless boiler

doctorman

trying to decide on a boiler, changing from oil to Gas.

2600 sqft house 2 zone baseboard (20:1 ratio) here in New York
The old oil boiler was 136kBTU and did a fine job till it gave out.

Decided to go with a high-efficiency unit so I can direct vent it and not use the air of the house, have high efficiency and lower fuel cost and smaller in size for the small boiler room.

the decision behind HTP UFT-140 was 5 years parts and 10 years heat exchange warranty vs, most others are 1 and 12 years warranty.
also price... at $1800 - 600 rebates

1) I understand I will not get 95% out of it with high temp baseboard but it wont be worst than a regular boiler.
2) I hear there is more maintenance involved with tankless... I have to read more about that but was wondering if the newer Fire tubes still have that issue. How DIY are those maintenance?
3) would installing a filter in the system solve anything? is it necessary? is that yearly filter change?
4) If not this system then what?

SeymourCates

The HTP UFT-80 is more than sufficient for your house. A decision to use the UFT-140 will result in its early demise.

You do not size a boiler based upon the stupidity of others.

Rich_49

Please tell us more about this house . I'm betting you do not need a 140 at all but would probably be very well set up with the 80 , possibly the 100 if the building is a sieve .

Magnetic filters like the Fernox TF1 is a good idea as is water treatment in any install . You can set it up for easy maintenance performed yearly by yourself .

Although you will not get 90%+ efficiency , you still have the benefit of modulation , Outdoor reset without worry of low return temps , and the ability to draw make up air from outside instead of through every crack in the home's shell which creates larger heat loss .

Gordy

The UFT is not a tankless. It is a medium mass boiler Modulating Condensing.

It is very possible your high temp emitters may still only need lower AWT for most of the year still benefiting in condensing picking up a few efficiency points.

If your envelope had insulation upgrades after initial baseboard was installed you may not need 170 AWT.

doctorman

The house is slab on grade, so it loses a lot of heat to the ground.
very drafty,
2nd floor is basically an under attic,
1st floor is tile directly on concrete.
shadowed most of the time
the windows are double pane but not the best,
tried to run a manual J and it in the coldest days it might get close to 110K so I sized it up from 100K to 140K that was one size bigger

the UFT model has 10:1 turndown ratio so it can run at 14KBTU if need be and only goes up higher as needed to my understanding. so I am not sure how I would affect the boiler by oversizing it if it can modulate to 14K BTU.

Fernox TF1 sounds great, thank you for that and looks easy to clean out by myself. so this would be installed on the return from the baseboard correct?

Any point installing the Fernox TF1 also on the incoming water to the house to protect the water heater tank etc? probably not.. right?

Anyone against using HTP UFT product?

any pointers in installing this unit, most plumbers I spoke with are not familiar with HTP, or even condensing units...

doctorman

searching to buy Fernox TF1, mostly European websites pop up, is there another filter that is used more often in USA?

Shane_2

I was going to say do a heat loss before picking a boiler. If you did that already, good for you. Many don't

I am a big fan of HTP. I have three UFTs installed in different homes. Would recommend them to anyone. Great support from their reps as well.

I happen to be a plumber, but many don't like to read the wall for some reason. Finding a good installer is more important than the boiler brand itself.

Gordy

Uft is a nice machine for the price point.

Your heatloss if done correctly is probably 20% padded.

Slab on grade without insulation ****.

Ironman

2600 sq. ft. I doubt if your heat loss is over 80k btus. I've been doing load calcs for almost 40 years.

The turndown ratio is to compensate for varying load because of varying outdoor temp; it's not to compensate for over-sizing. Running two zones means even the correct size boiler would be about 50% too large when only one zone calls.

The Fernox filter is not made for the fill line; it goes in the return line from the system. You're trying to filter what's already in the piping, not the minute amount that would come in with fresh water. Boyertown supply has them.

doctorman

Boyertown is in PA, I will call around in NY for the Fernox TF1 Omega.
Omega has 25 years warranty vs 2yr and seems to be the same price point.

so even though for coldest days I need 110KBTU, you suggest I use the smaller 100K BTU?
Will the modulation not correct for that?

probably most of the year I won't need even 80KBTU but those cold NY nights...Brrr, I guess we can put a big pot water on the stove to steam up the house.

How is a traditional boiler install different from a tankless boiler? what are the things that I need to make sure that my plumber is aware and does with these boilers that they might not be used to?

Gordy

Design day is not the coldest day ever recorded. Design day is a temp that your geographic area may go as low as about 1-2% of the heating season.

Oversizing a high tdr boiler relying on the tdr to compensate for it costs you up front money.

The low end of the uft 80 is 8k the 100 is 10k, the 120 12k and the 140 14k.

You have two zones. Rarely do both call at the same time. So if your load is 40k on each zone at design which is 1-2% of the season the rest of the season you will be short cycling that boiler.

Gordy

Food for thought your existing boiler is 136 k. If that was gross input it’s output is probably 95k at about 70% efficiency.

Did that boiler run for 24hours straight on the coldest day? I doubt it very much. Maybe 50% duty maybe.

mikeg2015

Use your oil use to size the boiler using heating degree day data. Or just click runtime at a given outdoor temp.

A house that actually needs 100k will consume a lot of energy. However, air leakage is tricky to model accurately because it involves stack effect and wind.

doctorman

good point Gordy, I will go for the UFT-100

I dont think they have 120k BTU

doctorman

between 100K and 140K unit
minimum BTU being 10K or 14K,

is that enough of difference to cause or prevent short cycling?

Leon82

How many feet of baseboard on the smallest zone?

Gordy

Hold on now that was an example. Have you paid attention to how your old boilers usage was? Records of fuel consumption to do a HDD profile as @mikeg2015 suggested? It’s a reality check.

Gordy

They do have a 120

SeymourCates

@doctorman

Answer a few questions and we can immediately tell you what the house consumed with the old oil boiler.

1) How many gallons of oil for a full calendar year? Specify the precise 12 month period for the info. Adjust for the fact that the oil deliveries are not precise in terms of a 12 month span.
2) How much hot water per day in gallons (estimate).
3) Location in New York
4) What is the setpoint for the 'stats? Night setbacks?

With this info, the heatloss of the house can be reasonably well determined.

doctorman

Leon82 said:

How many feet of baseboard on the smallest zone?

the ratio is 20:1 all over. I think 2nd floor is smaller at 800sqft
the rooms are not zoned out, it is just upstairs and downstairs
so 800sqft at 20:1 = so let's say around 40 linear feet smallest zone.
anyway UFT 120 vs 140
minimum of 12 vs 14 kBTU .. would that practically affect the boiler negatively?

KC_Jones

20:1 on 2600 sq ft so you have a total of 130' of baseboard?

If that's so the baseboard output on the high end of 600 BTU per foot the max your system can do is 78,000 BTU. A boiler any bigger than that is a waste. The 80 is the biggest you could possibly use.

Again this is NOT the way it's sized, just showing how you are absolutely going to oversize the boiler.

You should still run the room by room heat loss calculations.

doctorman

KC_Jones said:

20:1 on 2600 sq ft so you have a total of 130' of baseboard?



If that's so the baseboard output on the high end of 600 BTU per foot the max your system can do is 78,000 BTU. A boiler any bigger than that is a waste. The 80 is the biggest you could possibly use.



Again this is NOT the way it's sized, just showing how you are absolutely going to oversize the boiler.



You should still run the room by room heat loss calculations.

you are correct .. well I have a bit over 140 feet
even at 150*600= 90KBTU
so anything above uft-100 is a waste unless I add more baseboard.
I think I looked at it that way and still decided to go with 140K BTU because at the time I was looking at Westinghouse model in home depot which has only 140K option.
HTP has so many more models that I can go with 100K BTU

again in practice does it matter much 10 vs 14k btu minimum?

Leon82

yes, it will short cycle.
you probably will never need 600 btu per foot output. download the slant fin app and put your house contruction data I it and see what you get

my home had a 140k btu boiler
slantfin app said I needed 45k
fuel use said 35k

I went with a 55k boiler, the smallest they make and run lower baseboard temps

KC_Jones

The goal is to get the boiler to run as long as you possibly can. The higher the low end is the less chance you have of doing that.

With the mod con you would want to run outdoor reset which will vary the water temps to match the given load. That 80k (or whatever it actually is) is only on the coldest day.

Let's say in a warmer day you only need 120 degree water, the baseboard output is now 210 per foot, which on the 40' zone is roughly 8k btu. So the 10k will be close to running continuously, the 14k not so much, but the 8k on the 80 would be just right.

Again those are invented numbers as without the heatloss it's all a guessing game. Also why do you want to pay for something you don't need?

Don't round up you will regret it.

doctorman

KC_Jones said:

The goal is to get the boiler to run as long as you possibly can. The higher the low end is the less chance you have of doing that.



With the mod con you would want to run outdoor reset which will vary the water temps to match the given load. That 80k (or whatever it actually is) is only on the coldest day.



Let's say in a warmer day you only need 120 degree water, the baseboard output is now 210 per foot, which on the 40' zone is roughly 8k btu. So the 10k will be close to running continuously, the 14k not so much, but the 8k on the 80 would be just right.



Again those are invented numbers as without the heatloss it's all a guessing game. Also why do you want to pay for something you don't need?



Don't round up you will regret it.

In the layman head you would rather to pay 100- 200 $ more for higher BTU unit now than spending 5000$ later to change to a bigger unit.

okay I will redo the number as exact as I can and try to go with the closest BTU and minimum BTU.

you guys are awesome!

my final question:

What are the install issues with a tankless condensing vs a regular cast iron tank boiler so I can keep an eye on during the install and make sure my installer does not mess up?

Gordy

That the installer Reads the I/O manual, and follows it to a t.

Leon82

the pipes should look like the manual diagrams

Gordy

There was a day when fuel was cheap, and the installer put in a more than ample sized boiler, and emitter to not risk call backs of not enough heat.

Fuel is not cheap anymore, and call backs because the boiler is to small a rarity if the math is done correctly.

When you perform your heatloss figure what each zone load is. Not what the baseboard can produce, but what the zone the baseboard covers really needs.

No one on here said you need x size boiler. What was said is a 140 seems large for your home. Don’t assume anything until you perform that heatload calc.

Rich_49

Leon82 said:

How many feet of baseboard on the smallest zone?

How many feet of baseboard installed has no value in the discussion of what heat loss is . It only has value after heat loss is done to determine what SWT you can use or even that you may need to add length

Ironman

I'll also add that 600 btu per lineal foot is unrealistic. At 170* AVERAGE water temp, you'll be closer to 500 btus per foot. That means your emitters are only capable of about 70k btus output. It makes no sense to install a boiler that has more output than that. You're loosing efficiency if you do.

NY_Rob

You also never want to use 180F supply water for spaceheating on your mod-con.

You need 115F return water to get even mid level efficiency out of a mod-con. If your heatloss is so high that you need 180F SWT... stick with a high mass cast iron boiler.

KC_Jones

Ironman said:

I'll also add that 600 btu per lineal foot is unrealistic. At 170* AVERAGE water temp, you'll be closer to 500 btus per foot. That means your emitters are only capable of about 70k btus output. It makes no sense to install a boiler that has more output than that. You're loosing efficiency if you do.

Apologies, my comments were, in general to present to the OP how far off they are on boiler sizing. The comments are in no way for design or equipment selection.

doctorman

Zone 1:
so first floor on concerete/tile 1400 sqft with 100 ft baseboard
sunroom 300 sqft with 17 ft baseboard this is very poorly insulated area but used , we have to increase insulation and maybe add a radiator for this room.

Zone 2:
860 sqft with 36 feet baseboard + in wall radiator around 2 feet long
under attic

HDD in zipcode 11023
at 65 degree 4500
at 73 degree 6500


I do not have data from last years usage really.

did a full detailed Manual J again using coolcalc.com
it shows :
First flr 42K
Sunroom 14K
2nd flr 18K
------------
Total 74k BTU

Sunroom is my drainage and need to be insulated

So as everyone guessed 140K is way too big
so I will go with UFT-100
100K input will give me 80K output at 80% effciency
modulating down to 10K input (or 8k output ) that will give me good coverage.


feel comfortable with these figures...

anyone would like to add anything?

Leon82

> @Rich said:
> How many feet of baseboard on the smallest zone?
>
> How many feet of baseboard installed has no value in the discussion of what heat loss is . It only has value after heat loss is done to determine what SWT you can use or even that you may need to add length

I never said it did. He asked it if would short cycle. And is was after he was told his system would not accept the whole output of a 140k boiler

Leon82

If you got 74k load why would you still buy the 100

doctorman

Leon82 said:

If you got 74k load why would you still buy the 100

because at 85% efficiency 80 input will give me 68K output

Leon82

I don't think anyone calculates based on that.

KC_Jones

doctorman said:

100K input will give me 80K output at 80% effciency
modulating down to 10K input (or 8k output ) that will give me good coverage.


feel comfortable with these figures...

anyone would like to add anything?

Where are you getting 80% efficiency?

doctorman

KC_Jones said:

Where are you getting 80% efficiency?

the chart listed by NY_Rob above
baseboard heating with 140 degree return is 85% efficient

NY_Rob

36 ft of fintube zone.
210 BTU's /ft at 120F Average Water Temp.

36x210= 7,560 BTU's zone output with 130F Supply Water temp... which will just hit condensing range with 89% efficiency.

Why would you choose a 100K Boiler with a minimum turndown of 10K BTU's when it will without a doubt short cycle on your 36' zone?

The UFT 80W with 8K minimum output will be almost a perfect fit.

mikeg2015

> @doctorman said:
> between 100K and 140K unit
> minimum BTU being 10K or 14K,
>
> is that enough of difference to cause or prevent short cycling?

10k would run about 30% longer on low fire with the same load. So it’s significant that way.

But to throw a wrench in the works, the 140 will be slightly more efficient at a 30k firing rate than the 100 because it will have a lower approach temp. But probably talking less than 0.5%.

Ultimately despite being medium mass, I think increasing cycle time is the best goal to experience extend boiler life.