condensing boiler and Hi V

Mark_46

Guy thanks for all your feedback.

You say potential for condensing is BETTER at or below 180. But aren't the Hi-V water coils 180-200 devices?

Adjusting setpoints seems like something more for my installer but could you expand on how this is done? Do those adjustments occur within the boiler only or are the air handlers and thermostat involved as well? Is it mechanical or electronic/software? etc. Is a special tool needed?

Also, based on our discussion here and many others I have read on this site, it seems like a very good idea to have permanent in-line temp gauges installed at the inlet and outlet of the boiler? Perhaps even mandatory in order to get accurate measurement and subsequently proper set up? I can request this be done from my installer. [probably at extra cost! :o)] Any suggestions for best location, brand and type? Or does the Munchkin have them built in? If so how do you read the values?

Mark_46

Condensing High Velocity

Can I get some opinions on matching a condensing boiler with a hot water coil high velocity heat system? Is high velocity with a water coil considered a low temp hydronic system where a condensing boiler accels? Thanks.

Ted_13

depends on the coil

Most of the systems you see are DX cooling with an add on hotwater coil (anywhere from 2-4 row). I know that Spacepak also offers a water coil unit model WCSP which has a 6 row water coil which could work with 120º water. This unit uses chilled water for the cooling side.

Nikolai

HV system & Low Water temperature

Hi-velocity fan-coils (Energy Saving Product)work with water temperature range from 110F to 190F. With low water temperature, you get less BTUH and therefore a lower supply air temperature, it is imperative that the water temperature is known at the design stage. It ia a good idea if main plenum is insulated and vapour barriered.

Mark_46

Ted, thanks for

the feedback.

Our plan (but maybe not for long) is to use Unico hot water coils in the Hi-V air handlers for whole-house heating. Dont know how many rows they are though. But we also plan to use a Munchkin boiler which (just realized today) is really only for use in low temperature hydronic systems. Correct? If so,this configuration would not take full advantage of the munchkin's efficiency even though it uses input modulation. Is there such a thing as non-condensing input modulation boilers?


According to Heat Transfer's literature, boiler inlet temp is or should be 86 to 140 deg. I presume those are the temp ranges needed in order to have the correct amount of condensation which allows the 92% efficiency?

You also mention 120 deg water. May I ask why? At what point in a system?

Mark_46

So is it

correct to say that Hi-V hot water coils are high temp hydronic systems?

Ted_13

yes for add ons

With the add on coils you definately want hotter water. As far as the 140º I mentioned that was the lowest rating curve in the catalog. I'm sure Unico also has a water coil unit but I'm not familiar with it. With most any water coil airhandler you are looking for 180º-200º water @ 2-5 GPM to get any decent performance out of it. Don't forget that air doesn't carry heat nearly as well as water does and High Velocity systems use aspiration to mix the air dilivered from the outlet with the room air to equal a net air temp. On the other hand if you are putting in a radiant system (which requires 80º- 140º water) and just using the air system to temper fresh air make up then you can get away with lower temp water. A lot of systems that mix radiant with High V systems use and HRV or ERV (depending on the cilmate) which dumps into the return of the air system to distribute the fresh air throughout the house. These units use the heat from the outgoing air stream to heat the incomming air in the winter and the percentage of fresh air (from the HRV) to the return air stream (from the warm house) is small.

Mike T., Swampeast MO

A couple questions for you Mark.

Why the "but maybe not for long" qualification in the plan?

How many Hi-V air handlers?

Where are you located?

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I believe that all modulating boilers are also condensing boilers but not all condensing boilers modulate.

All condensing boilers THRIVE on low return (input) temperature--the lower the more efficient their operation. Lowered supply (output) temperature contributes to efficience as well.

Ted mentioned 120° water because it is possible to use a supply temp that low with high-velocity systems without having the air it delivers too cool. There is a catch however. Hi-V systems move significantly less air than traditional air systems--they are also optimized for cooling during the design process. The ONLY way they work for cooling while moving less air is by making that air significantly colder than traditional systems!

Translate that to heating and there can be some significant problems--less air moved means that air needs to be warmer than conventional systems to meet the same load. It's a VERY delicate balancing act--particularly if you're trying to use a condensing/modulating boiler. In general the more your summers are hot than your winters are cold, the better.

Nikolai

Condensing boiler and HV

HV fan-coil heating system works at any temperature range that provided by manufacturer it depends on what heat sourse is available: geothermal, hot water tank, solar, gas-fired boiler, wood-fired boilr etc. With condensing boiler it works without any problem but to get greater efficiency from the boiler we design fan-coil systems with EWT around 140F. Fan-coil size and number of vents have to be calculated based on EWT you use in your design.

Mark_46

Answers

Mike, Thanks for the response.

To your questions:
I am located in very Northeast New Jersey.

The plan right now is to use 2 Hi-V air handlers, one for each floor in the house/each zone.

I say "maybe not for long" because I realized today that a Hi-V water coil is a high temp system (180-200). It would be a mismatch with a condensing boiler that needs those lower operating ranges and reduce the munchkin efficiency level to that of a 'regular' boiler.

Heres my dilemma. We want to replace the steam heat system while adding A/C to a house that has no duct work infrastructure. Of course A/C requires duct work regardless so we started heading in the direction of Hi-V because the space issues and that those registers can be located on the floors or cielings, which we would need. So if we were already putting Hi-V in, I figured that it would be cost effective to 'piggy-back' the heat on the mini duct system. This would avoid having to install another infrastructure circut; eg hot water base board.

I have read good and bad things about Hi-V as primary heat. And now I come to realize today that Hi-V hot water coils are high temp and dont really match well with condensing boilers bringing the boiler selection into question as well.

And isnt Hi-V heat basically forced air? So would it be more wise to just use a conventional duct system? My installer, who I must say has been pretty knowledgable and I have confidence in states that conventional duct work will lead to stratification of the rooms. (hot head, cold feet and vice versa). This is because the first floor registers must be in the floors (up from the basement) and the second floor registers in the cieling (down from the attic). But is that true with smaller rooms like my house has? The price difference between conventional FHA and hydronic with any delivery type is SIGNIFICANT. Its hard to justify the price if I will only experince (eg) 10% more efficiency and comfort.

As you can tell, I am still unsettled with regard to system configuration. But it seems par for the course when designing HVAC systems ).

Mike T., Swampeast MO

Keep the steam.

Tony_23

Mike T.

There ARE modulating boilers that don't condense.

Baxi Luna 310i, Laars Endurance are two I have used.

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Mark_46

Ugghhh

Mike, your killing me ).

I thought I had put keeping the steam configuration to bed but you recommend it. Here was my thinking:

We want a more modern, efficient and cost effective system while adding A/C. Plus, our steam system is sort of a bunch of patchwork. The house was added on to in the 1970s and cast iron baseboard radiators were added. I dont think it was done correctly. The boiler is very old, the other radiators are mix and match types and who knows what the condition of the piping is on the inside. Steam requires tuning with regard to venting as you know, its noisey and I can tell you the house is NOT comfortable. If for no other reason it is a one zone system and the second floor is quite different than the first!

Mark_46

Fin tube, high or low?

Can anyone confirm if fin-tube baseboard radiators are high temp devices (180-200 deg)? I believe they are, correct?

Similarly, can a condensing boiler be used with fin-tube baseboard radiators?

Guy_6

Boiler

You are slightly mistaken in the thought that the Munchkin is ONLY a low temp boiler. The performance rating on the boiler is actually based on 180 supply and 160 return water. YES, it does THRIVE on lower temp water, but it is quite capable at the temps that you would need of 160ish.

Here I am promoting the Munchkin again... How about a nice little Smith GT???

Ron Schroeder

Mark

Fin tube will heat a space at lower temps as long as you have enough fin tube, however in an experament in my house a few years ago I set the bioler to 160 and the house heated to temp fine but I got complaints from the son and his wife upstairs that they were always feeling chilly because they couldn't feel the radiation effect. I had not told them what I had done so I turned up the boiler to 180 and the complaint went away.

Mark_46

Guy

Dont know if you read this whole thread but my plan was to use Hi-V hot water coils with a Munchkin. But the Hi-V water coils are high temp devices, Munchkin is better at low temps. I then asked if fin-tube baseboard could be matched to a modulating condensing boiler (munchkin).

But according to HT Products literature, the inlet temp is 86-140, outlet is 120-176 deg.

Mark_46

Bruce

You say fin-tube baseboard will work at lower temps if there is enough. That would limit me to how much outside wall linear footage is available, correct? Is it acceptable to put baseboard along inside walls?

Ron Schroeder

Mark

Outside walls under windows is preferred but you can place it on any wall that will get the job done

Guy_6

temps

That must be a misprint, as I KNOW from two years of training and tech. support there that the boiler is rated to 201. Again, the lower the op. temp, the more condensing and therefore more efficiency, but that boiler is fine at higher temps. You can always call HTP- they will tell you the same. 50 to 201.
On an air handler you should be able to set the water temp such that you will pull more than a 20 degree delta between supply and return, and condense quite well.
FYI, your post caught me, as I was at HTP, and am now with Mestek- the parent co. of Space Pak. I am trying to promote (to Mestek) a boiler/Space Pak combo similar to what you are doing, as I see it as a great combination.

Mark_46

Oh

Guy, It is a unique opportunity to speak with someone who worked for HTP!

The temp info you provide is interesting and now I'm completely confused ). You state 201 deg, for which model? All Munchkins?


Ya, HTP's literature states those temps on their website. I did call HTP and left a message but did not call back. It may not be such a good idea to refer to their promo lit as it could be inaccurate ). But I do not have access to any technical documentation. Do you?

You say the boiler is fine at higher temps. Do you feel it would condense enough and have the opportunity to modulate in a Hi-V hot water coil configuration?

As to Spacepak, as Im sure you know, they currently do not recommend their Hi-V system for primary heat. Unico does. So Spacepak wasnt an option right off the bat.

Do you feel the Hi-V is worth the extra $ over conventional forced air as I have talked about earlier in this thread?

Boilerpro_5

Sounds like classic problems

Which some simple tuning may solve. Noisy steam is NOT normal and unbalanced heating can be remedied by a good tech. If you want, every room can have its own thermostat with steam....not too easy with many "alternative" systems. Sorry to upset the applecart, but you would probably be throwing away a very good heating system and replacing it with one of the worst. HI-V cooling is great, from what I hear.

Boilerpro

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Guy_6

condensing

Yes, the boiler will condense in a Hi V application. Again, the lower you operate from 180, hthe better potential for condensing, so start at 180, then drop the setpoint 5 degrees and see what happens. I feel that you will probably end up operating at 160ish.
Due to the Hi V system, you will probably experience lower return water temps as well, therefore increasing the condensing.
As far as modulating, the boiler will do that all on it's own based on the return water temp, which is in turn determined by the air temp over the coil. As your space comes up to temp, the boiler will not have to work as hard to heat the coil, and will modulate down.

Keep me in the loop on this as it progresses. It's good stuff.

GW

Mike T., Swampeast MO

Sorry to do that Mark, but the location and age of your house don't seem to bode well for a combined HI-V cooling/heating system driven by a condensing or condensing/modulating boiler. You heat load is likely to be much greater than the cooling load which means you'll probably need quite warm air much of the time.

I'd really suggest a good and thorough review by a good steam man. If you search here you'll find MANY success stories of "hopeless" steam systems renovated to provide very good comfort and quite decent efficiency. On a small scale, steam will never be as efficient as [some] hot water systems, but their design an operation nature actually gives them some efficiency advantages compared to many hot water systems. When functioning properly a steam system is almost always operating at peak efficiency regardless of the load (weather).

Mike T., Swampeast MO

Thanks Tony!!!

Mark_46

Air volume

Mike,

I'm confused. According to Unico's web site, "Instead of typical units which operate at 500-600 feet per minute at the outlet, the Unico System operates at 2,000 feet per minute"

Do Hi-V systems move more or less air?

Guy_6

Temps

Ideally you can use 180 degree water, but I think that you will find that 165 should be fine. As far as setting the water temperature on the boiler, it is actually quite simple using the keypad of the boiler. The info is in the installation manual, but if that becomes an issue, contact me and I will take you through it.
A temperature gauge comes with the boiler, typically to be installed on the supply line from the boiler. I can not really name any gauges that I prefer, as I usually stumble upon one that I like and promptly forget the brand :-)
There is a simple way to look at the supply and return temps through the keypad as well. This is important as it shows you what the BOILER sees. Sometimes this is helpful as our reality and the boilers aren't always the same. Again, when the boiler is in, ask the installer to show you the diagnostic menu, which is where you can see what the control sees. Neat stuff.

GW

Ted_13

not so

Spacepak can be used as a primary heating source, in fact the coil performance is probably better than the Unico coil. What I tell customers in your situation is to leave the steam system add an 86% boiler with domestic water capabilities(http://www.embassyind.com/pdfs/embassyind_ambassador.pdf), put in the High Velocity system (DX) with hot water coil. You might even consider installing hte DX system as a heat pump giving you the option to choose which fuel you want to use most of the year. This type of system has options and redundancy.

Nikolai

IN & OUT temperature measurements

This digital temperature gauge can help you