Advice on boiler temp setting

[geoff07]

Of course, if you don't have a hot tank you don't need to be concerned about Legionella as long as any long hot pipe runs are flushed periodically. For those that do have tanks, a tempering valve (mixer) at the output from the tank is the solution to too-hot water.

The weather compensator doesn't affect the radiator settings, they remain as you want. It just reduces the circulating temperature. Ideally, the circulating temp will be just right to keep the rooms as you want them without constant changes to the radiator settings (heat gain = heat loss). But that requires getting the weather compensator slope just right for your building (thermal mass, losses, on/off schedule) and is a bit tricky to get right.

[Kovacs]

We have a Valiant Ecotec plus system boiler and HW cylinder. Recently I've invested in some independently controllable TRVs for the rooms both up and downstairs (the Pegler iTemps) and am happy so far with these as they allow us to not heat rooms/areas that aren't being used or at the least, have good control over the temperatures in those rooms.

Further savings should also come from the Tado thermostat and boiler controller that have been installed which amongst other things, will use presence detection to pick up when the wife and I are out of the house and reduce the house temperature according to how far away we are.

Reading on here though, as we do have a condensing boiler and I understand that the flow temps ideally want to be moderated depending on the outside temp, which weather compensator would do the job? Most of the ones I've seen want to be your thermostat/timer as well, but I don't want or need any of that. I'd like to just ensure the flow temp is set to an optimum level. Any suggestions on what would be a good option for this?

[martyn.wendon]

Reading on here though, as we do have a condensing boiler and I understand that the flow temps ideally want to be moderated depending on the outside temp, which weather compensator would do the job? Most of the ones I've seen want to be your thermostat/timer as well, but I don't want or need any of that. I'd like to just ensure the flow temp is set to an optimum level. Any suggestions on what would be a good option for this?

I had a new Vaillant combi boiler installed about 3 years or so ago to replace an ageing 30+ year gravity based system. At that time, I was using the HouseHeat / ELV / Conrad FS20 based thermostats, radiator valves and boiler interlock to great effect, but I was persuaded by the gas installer to remove it all and fit the Vaillant weather compensator instead. What a bag of poop that was :-(

As a family we just couldn't get on with it, the heating seemed to be on nearly all the time, like coming on "gently" at 3am just so that by 7am when the schedule was supposed to kick in it was "warm" for the hour we have the heating on in the mornings. Or refusing to come on at all, even though the house felt chilly. I understand the principle of weather compensators and I persevered with it for a couple of months before finally removing it and re-fitting my previous solution :-)

Since I already had full control and reporting of the radiators and boiler I just use an input into my HA system from an external temperature sensor. When it's colder outside, I set all the rooms set-point + a few degrees. When it's warmer outside, I set all the rooms set-point - a few degrees. I also measure and record the temperature of the flow and return pipes in the HA system and then set the flow temp on the boiler and balance all the radiators at the lock-shield end to hit a sweet point on the return temp. This works really well - I know it's not *true* weather compensation but it still saves money and compared to the mess with the Vaillant weather comp at least it has family approval!


Hope that helps!

[geoff07]

If your boiler manufacturer makes a weather compensator, then that is likely to integrate better with your boiler, possibly even physically in the cabinet. Though the report above isn't too promising in the case of Valliant. Ideally, it would adjust the setpoint in the boiler electronics directly. In my case, the WB condensing boiler at my house only has room-stat on/off control, so I made my own weather compensator with a relay that takes the place of the room stat. It does the job well but is another box on the wall, and makes hot-water priority a bit more of a fiddle. I also have the Conrad actuators, with their gubbins that listens on the radio to the radiator settings and cuts out the boiler if there is no soft-zone demand.