Efficiently using gas heating system

ravendude

Had a bit of a saga recently (www.boards.ie/vbulletin/showthread.php?p=83114481) with our heating system that is now for the most part resolved.

The installer was working on the above issue and noticed a timer schedule I had written up next to our timer controls.

We had been running the heating quite intermittently on the timer - running zones at separate times for a couple of short periods during the day.
When the house started to get cold, and the rads were also cold, we would hit the boost button (which turns on the zone for 1 hour).

We also had the rads in some of the rooms off.

The installer is saying that we are using the heating inefficiently by doing the following:
1/ by having it on for short periods and heating from cold for these periods. He says its better just to have it on all evening and let the house warm up properly
2/ by boosting from cold
3/ by heating zones separately (hot air is drawn to the colder zone). He says its better to have some overlap in the zone schedule
4/ by having rads off in several rooms, he says it is not all its cracked up to be unless the doors are very well sealed (and internal doors are not generally sealed enough), ie. - hot air gets drawn into the colder room.

We left the heating on from 5.30 to 9.30pm yesterday evening and the house was certainly lovely and warm all evening
We have thermostats, but most likely due to where the thermostat is in the long hall downstairs it never really reached the 20 degrees to go off and mostly sat at 19. (It might make sense to turn down the thermo)

Even if the thermo doesn't knock off the heating, - is it a case that the boiler is more efficient at just keeping the water up to temperature over a longer period, than heating from cold all the time?

ravendude

Quick question related to the above..
Does the boiler fire all the time until the room/house temperature reaches the temperature of the thermo on the wall?
...or does it just fire until the water is at the temperature set on the boiler?

ie. is my boiler burning gas all the time while the house/room temperature is below the the thermo control temperature?

L1979

Control on boiler should cut boiler when the return temp reaches set temp on the boiler. The circulating pump will continue to circulate, providing hot water to rads & cylinder.

Thermostatin the hall will monitor the temp in the hall, and will cut boiler and circulating pump out when it reachs eset temp.

I would suggest that your installer is correct in pointing out inefficenies, but should have spent the time to explain how your system is configured so that you would be in a position to make changes to the themostats etc to suit your own comfort levels.

I have a similar setup in my system and i would normally have the thermostat in the hall set between 13 and 15, depending on weather! If you reduce your thermostat and work upwards, making subtle changes, you wont over heat the house and thus make it uncomfortable for the evening.

Enjoy fiddling!

shane0007

L1979 wrote: »

Control on boiler should cut boiler when the return temp reaches set temp on the boiler. The circulating pump will continue to circulate, providing hot water to rads & cylinder

No it doesn't. The boiler cuts out when the flow temperature is reached & not the return temperature. Modulation reacts to return temperature.

ravendude

shane0007 wrote: »

No it doesn't. The boiler cuts out when the flow temperature is reached & not the return temperature. Modulation reacts to return temperature.

For the home user, is the result the same though? ie. boiler not eating gas when the water is at temperature? ie. boiler is just working to keep the water up to temperature?

I guess its like comparing the efficiency of one of those hot water dispensers you'd get at a canteen as compared to boiling a kettle frequently from cold water.

shane0007

ravendude wrote: »

For the home user, is the result the same though? ie. boiler not eating gas when the water is at temperature? ie. boiler is just working to keep the water up to temperature?

I guess its like comparing the efficiency of one of those hot water dispensers you'd get at a canteen as compared to boiling a kettle frequently from cold water.

The answer depends upon the boiler being used & the controls that are in place. If full & proper boiler interlock with time & temperature control is in place as it should be, the boiler is a Band A Gas Boiler, then the gas boiler will modulate to suit the exact demand at that moment. Once the desire room temperature is reached or dhw temperature is reached, then electrically the boiler will shut down until demand is requested again.
On the other hand, you could have a Band A oil boiler or a Band D gas boiler & the sucker will short cycle til it's hearts content using excessive fuel unnecessarily until the desired room or dhw temperature is reached.

antoinolachtnai

My own experience the last month or two is that I can get good comfort and economy by running the heating at a lower setting and for a longer period. Perception of comfort is subjective, I know.

I think this works because the boiler's condensing feature can operate to a greater extent when the water is heated to a lower temperature. The boiler manufacturer's documentation appears to bear this out (though they don't make it very clear).

A suggestion for your fiddling is to get a few cheap digital temperature sensors. I got some from dx.com. http://dx.com/p/digital-compact-lcd-thermometer-with-outdoors-remote-sensor-15553?rt=1&p=2&m=2&r=3&k=1&t=1&s=115002&u=15553

It is also obviously important to read the gas meter frequently.

Lower settings are not much use for heating domestic hot water, so I had the system was installed (in accordance with manufacturer's recommendation) so that I can set the hot water at one setting and the central heating at another. If you don't have this, my approach won't be much use to you (anything you save on heating the house, you will probably lose on heating the water with electricity).

The next step for me would be to get a temperature compensation sensor suitable for my boiler. This would mean that the central heating water temperature would get hotter as the outdoor temperature got colder. On a warm day, the heating might not go on at all. According to the manufacturers there is another 2 percent saving to be had from this across the season.

Not relevant for you, but I may also add some radiators (or add some extra sections to the radiators I have). The benefit of this is that I will be able to get the same amount of heat at a lower temperature, and hence a little cheaper.

I am open to correction on any of the above, of course.