Reply to Thread

Hey Rogertc if you want to send me an Email. I will try to help further.
Sorry, email addresses are not permitted in post, please put it in your profile, thank you.

Originally Posted by ICE Service

Too much air can cause a low temp rise... What unit are you working on?

htdm 1000,

Too much air can cause a low temp rise... What unit are you working on?

I've have just found out I have same issue. 20 degree rise only. I do see where I'm 2900 over design cfm inlet. Has anybody found a cause yet?
Newbe here

I do remember this Job. I will send you the unit specs later today.
These units do have a very low temp rise.

Ben! That was u I was refering to in my otber post. Hows things? Remember pitt meadows arena?

If you can send me a model and serial number I can help with this problem

The control board was called ICECON, and from what little I recall the software was of the same name, but it came on an unmarked CD. You have to contact ICE for it. These low temp rise units were Canadian made vs. the U.S. made high temp. rise units.

Issues were the temperature sensor location, the set points which are factory set on the board according to the model, the Johnson modulating gas valve, and the feedback signal to the board on the combustion fan. Don't know if the low rise units are listed as condensing, but as far as I am concerned, they're real close to it. Can't explain the two condensate drains they have any other way. The U.S. high rise version does not have them.

What type of program is hooked up to the systeam?

I have never touched an ICE unit - but they seem to be in the same category as an EVAPCO system, where they do custom design for each application. That being the case (along with my usual disdain for mechanical engineers - sorry guys!) I would check the design of the system itself - Board is calling for 100% - 10v dc output - valve is open - but is the valve the right size? Is there excessive pressure drop through the gas train? If you know your airflow - then you can also know the Btu's needed to get the temp rise you need - then cross reference the Manufacturer's specs on the valve to be sure that it will be able to deliver. If you need help double checking the sizing on the gas train - I have a reference that will help with that.

Also check that the gas pressure doesn't drop when the system fires - sometimes the pressures look good until the system starts.

I had an EVAPCO that was delivered with an undersized TXV because Evapco did not account for the pressure drop across the distributor. When the weirdness starts - do not assume anything is right on a custom system.

Look at these google searches:

www.ice-ww.com/HTDM%20Installation%20Manual.pdf see page 27


http://hvac-talk.com/vbb/showthread....etup-questions


Sorry, that software, laptop and special cable was left behind at the location those units were at. Happy not to have any of those HTDMs. Ours all ran stand-alone with an on board thermostat. Can’t see how a BAS can help anything. Some of your problem may be that the BAS control setup was not done for real life conditions, and again these are low temperature rise units that are supposed to run continuously.

Originally Posted by breegle1313

There is a software that you have to plug a laptop into the board on the unit and you can read the rpm of the combustion blower and the percent of gas at all six stages. They are all where they are supposed to be. I am thinking that the heat exchanger might be getting clogged because of the draft reading of the flue and the lack of the transfer of heat from the heat exchanger. My coworker swears that it cannot be the heat exchanger being clogged because there was no black soot coming from the flue.

I dont mean to post incorrectly, but I cant find a way to private message.
You mentioned the software, is it possible to get a copy of that software? Totally unrelated topic as I am taking over a unit with a BMS and need to verify some settings but I cant seem to find the software they talk about in the documentation to be able to do so.
Thanks in advance!

coolerik
View Profile View Forum Posts Private Message Add as Contact View Forum Threads

Professional Member Join Date:Oct 2005
Location:B.C. Canada
Posts:387I remember doing startup on a very similar unit with the tech from ice and he mentioned that these units have a very low temp rise, like 20 to 30 on high fire....mabey the units are opperating correctly and just not being used for the right application. Have you talked to ice about this? Im thinking this might just be a possibility

My experience with ICE units is similar. We had about a dozen non-Icecon controlled units which worked great, and they are high temp. rise units. The four newer units controlled by Icecon boards are low temp. rise. You should check with ICE to determine if the settings on the Icecon are proper, as they were the only ones who could program the boards and match them to the unit application. I had to purchase an extra board to keep a unit running when I returned the old board to ICE for service which took a long time. They said not be interchange the board with other units too. These type of units worked best in enclosed areas where minimal cold air entered the zone, not as air turnover units in a large factory setting with the big doors opening or where there was a lot of exhaust. The software to communicate with the board would only work if the board was 100% functional. If there was a malfunction, you could not cummunicate with the board to aid in service. If we need any new units, nothing with an Icecon board is coming in again.

I remember doing startup on a very similar unit with the tech from ice and he mentioned that these units have a very low temp rise, like 20 to 30 on high fire....mabey the units are opperating correctly and just not being used for the right application. Have you talked to ice about this? Im thinking this might just be a possibility

I would Perform a combustion analysis on the units and compare/ review manufacturers specification on readings, there is something causing this reduced temp rise.

Beta

Originally Posted by hvacrmedic

Is this unit is pulling 100% outside air?

The unit is using zero percent outside air as a make up air. the only outside air that the units use is for the sealed combustion and they need to use that due to the negative pressure of the building.

Originally Posted by Betabass

Are your AHU making up the exhaust air by bringing outdoor air back into the building??

no, there is no makeup air on the AHU's besides the one but the dampers are closed completely.

Verify design gas pressure. Measure with all units running and check static pressure. The design of the ICE heat exchanger requires some static to scrub the exchanger. What kind of discharge duct is there?

So he needs to check air velocity and verify air flow using the equal friction method, or perform an air balance and confirm the delivered air. Although it is very unlikely that he is moving that much air to over come the required temperature rise.

Again this is a completely sealed combustion which requires 100% outside air. Combustion air is normally delivered by an inline fan and draft by a roof ventilator. It's very common that there is a VFD for both combustion air and draft, however the OP has not stated actual configuration.

Draft will normally be set at a slight negative say -0.10" WC as an example and combustion air at 0.00 " WC. This is a basic design for start up but will need to be corrected based on his design criteria.

but if you take down the CFM going. I think they need that much air going in. If you block the air coming in it would raise temp but you would not have the air you need.