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Question DetailsAsked on 12/27/2015

Oil fired, steam boiler. No gas. Solar H2O. 80 gal 2 coil tank. Boiler doesn't heat water. Advise H2O heat options

The Burnam boiler for some reason doesn't heat the hot water very well

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2 Answers


Obviously not knowing the configuration of your system, all I can do is run through a list of what I would look at to try to troubleshoot it. I am assuming you did mean STEAM boiler, not hot water (hydronic) system - if hydronic feeding hot water in-floor or baseboard or water (as opposed to steam) radiators, operating temp would be lower - typically 180-200 degree shutoff temp :

1) are burners firing - do they look like they are firing correctly, mostly a fairly tight jet or bulb of flame of a brightish yellow - not billowing out with significantly feathery or cloudy edges or tendrils comings out, not dull orange or red, no splattering of oil or soot buildup, no significant flickering, no screaming or whistling sound (many will have a dull roar when burning), uniform appearance at all jets/nozzles (burners) if you have more than one. Granted, with a lot of models you don't see much of the firebox, so you are limited in what you can see - tougher to assess by eye than many gas furnaces. Problems can include improper air mix, inadequate oil feed or pump pressure so it is not getting the right amount of fuel or is not atomizing correctly, etc.

2) is boiler itself getting up to temperature (whatever yours is rated at - likely around 220-240 or steam, but check rating plate). If not, during firing cycle, is the secondary or safety thermostat (commonly clamped to outbound piping) shutting it down prematurely so it does not get up to temperature ?

3) are gages accurate - check for approximate match to gage reading at outbound piping from boiler (when circulating) with a thermometer of appropriate temperature capacity, held against pipe with a dry towel or insulation (to keep it at pipe temp even though not in good contact) - use HEAVY gloves when doing this - or use laser thermometer if you have one. Check water temp in storage tank by draining a bit out of the tank into a bucket (carefully) and check temp as draining.

4) did any valves get shut off - blocking flow at some point

5) are pipes to the radiators (near to the boiler but on the "house side" of the zone valves, getting hot when the thermostat is calling for heat - perhaps the zone valves are not operating because one or morethermostats are mis-set, still on A/C setting, or batteries are dead. Or one or more zone valves might be dead and need the valve (or more commonly just the power head) replaced.

6) Is the control valve from the solar H2O system working right - should have a thermostatic control valve that shuts off the flow to/through it when the temperature in the solar collector is below the rated incoming temperature (except for a trickle flow amount to keep it from freezing), otherwise you are just heating the great outdoors. I have seen several systems where for about 9 months of the year and during the night the other 3, they were radiating heat to the great outdoors instead of heating the house because the system was circulating the 70-100 degree return water through the collector, actually dramatically increasing rather than decreasing the heating bills. In fact, when used with combined tank systems or household heating, without a heat pump solar water systems tend to be very iffy and commonly a wasteful system, because they rarely (and even more rarely in heating season) heat the water to the point where it is warmer than the steam/hydronic heating system return temperature. Domestic hot water heating can be a different story in sunny areas with good sun angle exposure, because it is competing with incoming 36-50 degree water from the supply source, so not too hard to beat that, though if used 24 hours can still be inefficient when outdoor temps drop below the ground temperature at night.

7) is water flowing through both coils correctly, is one blocked ?

8) if this is a new situation this does not apply - but if say a new house for you so you don't have prior history with it, try to trace the water flow - generally, for systems using solar heating of the heating system water (which is fairly rare in itself), the return water provides the feed to the solar coils, with them feeding back to the boiler as the incoming feed - this assuming an integrated system. Is it plumbed so the return feed or solar feed is going straight to the tank, bypassing the boiler, so cooling it ? This situation can also occur if a bypass valve is left in the wrong position. (Note - some systems use a heat pump to boost the temperature of the water coming from the solar collector, in which case the feed might be straight to one of the coils in the tank - lot of possible variations how it works if a heat pump is in the picture.)

9) if system is gurgling, may have too much air (or water with a steam system) in the piping, so may be vapor or fluid locking - circulation in the heating loops being restricted or prevented because air (in hydronic system) or water (in steam system) is putting too much back pressure on the system for circulation to occur correctly.

10) is system pressure right - with steam system almost always under 2 psi, commonly under 1 psi opeating pressure. With hydronic (hot water) systems commonly run at 1/2 psi per foot of rise to the high point of the heating loops (so about 10 or 15 psi in a two story house or two story with boiler in basement, respectively), plus 5 psi - so commonly in the 15-20 psi opeating range - but do not exceed about 90% of the rated OPERATING (not TEST) pressure on the nameplate.

11) is circulating pump working - some run continuously, some turn on when the zone valves open

12) if a more modern condensing boiler (plastic vent pipe with exhaust fan in it), make sure fan is running when unit is firing (though it should shut down within 15 seconds or so if it is not), and that the exhaust flue is not blocked by insect or animal nest, frost, etc.

13) improper water level (steam boiler) - too high a water level in a boiler can limit or eliminate steam production - your system hopefully has an automatic level control and fill system to keep the water level right. If hot water boiler, automatic fill valve or pressure tank may have malfunctioned, so not enough water is getting into the boiler.

14) has system been drained and flushed periodically - or is it building up sediment and minearal accumulations in the piping that could be restricting flow

15) of course, if burners are not burning at all, or start but then shut off before up to temp, could be a number of cuases, starting with safety switches detecting inadequate air to the burner, failure of flue fan to start, flame rollout, overheating in the firebox, etc. Most of those issues are not DIY unless you are a pretty hard core DIY'er, because it takes some mechanical and electrical savvy to be able to test each for whether it is properly shutting the system down, or is malfunctioning and giving a false safety reading.

If these ideas don't help you figure out the problem, then you need a Heating and A/C (your Search the List category) technician to take a look at it.

Answered 3 years ago by LCD


Oh - and because you have a 2-coil 80 gallon tank is almost certainly a combined domestic hot water and heating system, so with a solar water heater you are going to need a Heating and A/C technician who knows both - or may end up having to get an HVAC tech to look at the system, and then he may say it is a problem with the solar system - and of course that tech may say it is an HVAC problem, etc, etc - so best to try to find a company who has a tech (or maybe 2 techs) who can cover ALL parts of the system in one visit.

Answered 3 years ago by LCD

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