Munchkin M80 boiler not heating enough.

lunsworth

I Have a m80 munchkin that doesn't produce enough heat. I serviced and cleaned the unit. I don't have any error codes. I have about 14 zones in a warehouse 60x45 but even if I zone it to 3 valves we cant get it over 55 degrees running nonstop. The water never heats above 118 and usually stays around 110. the more valves open the lower the max heat. building is about 23 feet high. I just called HTP and the said it could be the return supply sensor. Any thoughts. Thanks

JUGHNE

Does the read out show you the fan RPM?

Fan speed is what controls the firing rate.

5000 RPM or so might be 100% firing.

HomerJSmith

3600/3800 rpm is full fire. Infloor pex or baseboard or wall panels??? What does the display panel show as to the temperature (118) all the time? What size pump on the sys? Insulation and ceiling height? What is the winter conditions where you are? You can't add more heat to the building than the boiler is capable of delivering. 80K at sea level.

JUGHNE

That 4-5000 RPM is for a 199,000 btu input.

EBEBRATT-Ed

Did this just start or did it ever work?

lunsworth

Sorry I didn't get back sooner. I thought I would receive notifications and didn't. I need to do some homework on the questions you have all asked and get back. I never had it set high as I used my shop, only to 50 or so, but a new renter wants it higher so I'm not sure if its a new problem. It did seem though when it was installed new we could set it in the 60s and it would at least get a higher heat in the waterline. It is in floor pex. Not sure on the RPM or pump size so I will check. Its Utah desert winter. occasionally gets to single digits. usually around15-25 at night. 40-55 in the days. Building is cinder block. A plumber recently told me if the builder didn't put insulation around the outside of the building around the foundation a lot of the heat would leave that way. I don't believe he did.
The water will get higher if I continue to close the valves, but only having one open wouldn't do much. Still it would only reach the 130s maybe and not get higher.

Alan (California Radiant) Forbes

80,000 BTU x .90 efficiency = 72,000 BTU

72,000 BTU divided by 2700 sq. ft. = 27 BTU/sq. ft.

Just guessing, that boiler should be sized properly and your phrase, "I have about 14 zones in a warehouse 60x45 but even if I zone it to 3 valves we cant get it over 55 degrees running nonstop." is telling. Something is restricting the output of the boiler.

Have you had your boiler serviced recently? Just cleaning the heat exchanger, doing a combustion analysis by a person that knows how to read the numbers, washing down the condensate drain...........can turn up the problem.

hot_rod

118 should be plenty for concrete slab supply
How many loops in the slab?

lunsworth

When in test mode the rpm was 3210-3220. I noticed the small clear tubing from one of the vents was off, also I remember a plumber bypassing one of the valves many years ago. I dont know if any of that makes a difference. Also, their is 9 total loops. Thanks for all the help. I did just service and clean out the chamber and condensation line. Im not sure anyone local can do a combustion analysis so maybe I will try to find someone.

lunsworth

clammy

That’s the water pressure switch that was jumped . From the looks of the inside cabinet I would say that the swirl plate and the Venturi inlet should be clean also generally the inside cabinet . How old is the boiler and the system ? Generally I used to replace the swirl plate before they became brittle from age and destroy the blower . What temperature difference are you see across the system loops and what difference across the boiler ,this is after the system has been running a few hours not a cold start . What pressure is the system operating on it should be at least 15 to 20 . Also replace that water pressure switch its most likely clogged while your at it flush the boiler and check the condition of your water if dirty then most likely the original contractor never cleaned and flushed the system properly. If so flush then clean and flush then system and add and conditioner and inhibitor . It may be that the system was never been designed to supply more then 55 degrees indoor temp in which case supplant heat would be required .
Peace and good luck clammy

hot_rod

looks like it is breathing pretty un-healthy air if it is pulling from inside the building?

Dust will grind up the inducer motors also.

Is it non barrier tube, white colored is usually plumbing pex.

If so, I would pull the top off the Honeywell air separator. That is where they can sludge up from any corrosion in the system.

KC_Jones

I didn't see it mentioned, so I'll ask. How long did you let it run before you determined it isn't heating properly?

lunsworth

Its been running for weeks. The tubing is orange. The pressure is about 12 which the local hvac guys said was right but maybe more pressure is needed. I will see what the manual says. Ive never purged the system or added any treatment but I can try that.

Teemok

If the fan is spinning at full firing rate and combustion reading are at spec. and there is no boiler water path clogging, you can take accurate temperature measurements ( thermistor strapped to pipe and insulated ) of the water leaving the boiler and returning to the boiler and subtract those two numbers to get the Delat T. You can then estimate the flow from a pump curve and boiler flow vs pressure chart. Then you can do the math for BTU's/hr being delivered. Math: Boiler flow (GPM) x 500 x Delta T (difference in temperature of supply and return in F) = BTU/hr. If it's near or above 72,000 the boiler would appear to be doing what it is designed to do. The depth that tubes are set at in the slab, slab thickness and the difference between indoor air and slab surface are factors in how many btu/hr that slab would need to warm up.
After three weeks the slab surface temperature, measured 10' from foundation edge in areas the loops have been heating should be noticeably warmer than indoor air.
If the structures heat loss is greater than 72k btu/hr it will never completely warm up the air.
If you restrict flow to just a few loops you have limited slab areas reducing emitter area (heated floor area) and it will not heat the space well.
If the flow in the loops is not balanced you are not heating the whole slab evenly and slab output will be limited.
If the slab is covered with an insulator it will limit capacity.
The thermal mass of a 2,700sf 6" thick slab is substantial. If going from 36F to 80F slab temp., it's over 2 million BTU's or 28 hrs at 72k/hr. Trouble is, heat is lost while you are heating all that mass so a three day burn might be rational. The mass of connected block walls added makes it even harder to heat up.
Small boiler, hard job.