Controls for a ecotec plus 428 boiler

[fullofit]

Either way I don't see you getting it working 100% fine due to the default behaviour of the boiler being suspect. Have asked a few questions on the forum for people who say they have it working 100% fine but never get a full answer to my questions. Quite possibly with a commercial circulator it may be possible for CH but DHW generation I just cannot see how it cannot suffer from micro firing when nearing full tank regeneration

Well, I have a 415 which works 100% and doesn't micro fire. The important thing is to match the flow rate with the first minute's firing (about 75% of max boiler output) and subsequently d0. However, you're stuffed from the start if your boiler is significantly over sized.

A 28Kw boiler requires a minimum flow rate of 20 l/m at 20c but you can get away with about 15 l/m if d0 is set <= 75% of max output and d2 allows for sufficient cool down.

The pump only needs to match the index circuit and therefore there isn't necessarily any benefit in using a beefier pump, only disadvantages (high water velocity, noise, higher operating costs). In fact, I'm using a 15-50 on the minimum setting.

 

[jeffridj]

Hi, I left the settings as you suggested all day (d0 = 15, d1 = 12, d2 = 60 and water temp 68c) and the living room never got up to temperature all day, stopped at 19.5 with an outside temp of 1c. I've now put the water temp up to 75c and the temp is now a more respectable 21c and still rising so far. The other settings have been left alone. Will leave it like this for tonight and see how it goes.

 

[scoobydo123]

Fullofit how about when on hw? Can you dissipate enough heat when the inevitable cycle happens when the cylinder is near to satisfied? What cylinder do you have as well, rating of coil? How far from the boiler is the cylinder and what size primaries. What flow temp are you set to as well and are you radiators oversized for the room? TRV's on all rads apart from where stat is?

thanks

Jeff

Are you getting microfiring? Are you radiators the correct size for the room? What you possibly got was micro firing with the lower flow temp I get this on mine so have to crank the flow up to ensure that target flow is not reached too quickly.

 

[jeffridj]

I've checked the sizing of the living room rad and it is just under 10,000 btu which is exactly what the online calculators suggest.

I have never noticed any problem with the hot water, it always seems to be up to temp within 20 minutes or so in the morning and I think it's a 40gallon tank.

For the first time in some time, tonight the heating has been fine. No cutting off and the living room temp stable at 21.5. I'll leave it alone now before I break it! Thanks again for all your help.

 

[Agile]

I would put that down mostly to setting d0 correctly to match the heating requirements because as I had expected, the boiler is obviously oversized.

Try measuring the firing/resting times now when the CH is up to temperature.

When the weather is a bit warmer you can turn the CH down to 70 C or eaven a little lower if it still gives enough heat output.

Tony

 

[jeffridj]

It now seems to do a number of short cycles - off for 1 minute then on for a number of seconds starting at about 20 and increasing each cycle until the water circulating temp gets down to about 55c during the off time and then I get a more extended burn of maybe 10 minutes or more. When it is on the more extended burn you can hear the boiler moulating down as soon it gets near to the 75c mark. Should I do any further adjustments?

 

[Agile]

Hopefully.

Lets see what Fullofit and Scooby think about resetting the other parameters.

What are the d40/d41 when its doing the 10 min burn?

Tony

 

[jeffridj]

Heating has just gone off now as we have reached the room stat temp and that hasnt happened in a while! From memory the d40 was hovering around 74 and the d41 was around 66. I also checked the d36 flow? and that showed 0. I assume flow isn't measured on this boiler?

 

[scoobydo123]

Jeff

Yes hot water generation will be fine (ie you will get HW), have you got it on timer or constant? What you may find is that if on timer you are masking the short cycling or may not have noticed it. The scenario is HW only, draw off some hot water the cylinder stat will then call for heat. Likely the boiler will not be able to satisfy the cylinder on initial burn (ie first burn long). Once the primaries have cooled enough the boiler will re-fire but at the inflated rate and will probably only burn for 15 seconds and then cycle until eventually cylinder is fully satisfied or the timer turns it off. Obviously you can get round this by having the flow substantially higher than the stored water in the hope of completing water generation in the first burn at the cost of gas use for the system as a whole.

The advanced controls go someway to getting round this as it will adjust flow temp upwards as HW generation can be put as priority then it will go lower for CH demand.

Flow not available - correct

 

[Agile]

The d36 is the hot water flow rate as used in a combi boiler.

It is derived from the rotation speed of the flow sensor which is a plastic water tubine with an embedded magnet inside. On the outside of the case is a Hall effect sensor which gives out a pulse every time the turbine rotates and therfore a signal whose frequency depends on the flow rate.

Tony

 

[jeffridj]

Scooby - The hot water is controlled by the aq6000 so it has priority and it is on morning, lunchtime and all evening. The set temp is 55c and we have never ever run out of hot water even with 2 teenagers and a power shower lol. As you say, I may not have noticed if it is cycling, but it does certainly get up to temp and the radiators get hot within about 20 - 30 mins of the heating coming on.

 

[scoobydo123]

Yes you will get your hot water just perhaps not generated in the most efficient manner it probably gets to within 3 or 4 degree C on the initial burn but will take a long time to get the last few deg C.


I first noticed it during the summer months when obviously no CH demand. I was removing a gas cooker and could hear the boiler misbehaving. During the winter months effectively your system is much larger so quite possibly masked. I have looked up your stat and cannot find much detail apart from a couple of scanned pages not detailing everything it can do.

Still at least you have made progress

 

[fullofit]

Fullofit how about when on hw? Can you dissipate enough heat when the inevitable cycle happens when the cylinder is near to satisfied? What cylinder do you have as well, rating of coil? How far from the boiler is the cylinder and what size primaries. What flow temp are you set to as well and are you radiators oversized for the room? TRV's on all rads apart from where stat is?

Radiators are sized for higher temps, flow temp 65°C, trvs on all but two rads, auto bypass turned down as flow through non-trv rads is sufficient. Cylinder is blue jacketed about 5m from the boiler, so nothing special. Hw is timed and cylinder stat turned down to prevent boiler cycling near setpoint. Cylinder will reheat within one or two firings.

 

[fullofit]

It now seems to do a number of short cycles - off for 1 minute then on for a number of seconds starting at about 20 and increasing each cycle until the water circulating temp gets down to about 55c during the off time and then I get a more extended burn of maybe 10 minutes or more. When it is on the more extended burn you can hear the boiler moulating down as soon it gets near to the 75c mark. Should I do any further adjustments?

A flow temp of 75°C will only give you a one minute cool down period which is insufficient to prevent cycling because you're looking for a 20°C drop.

And as you've already said, a lower flow temp doesn't heat the house enough, there isn't much more you can do.

 

[scoobydo123]

Fullofit


Yes that is the key for HW with this boiler is to set cylinder stat low if it doesn't fully recovery on the first burn then I have seen it getting stuck on short cycling.

Still I think I have a light at the end of the tunnel