Real world testing example of Condensing Boiler in older home

[JC22024]

Simple rad Calc will tell you all you need to know

Yes I'll look into formulating that for both zones and posting. Some rads like the new mysons I'll find data for. Some of the 40 year old non Finned rads could be trickier to determine but I'll fully measure up and look for calculators

 

[ShaunCorbs]

Mins half the output for non convectors

 

[JC22024]

Update, I did go ahead and jet my boiler down to 0.5gph nozzle / 20kw with interesting results.....



With the BEM switched off / overrode and on the downstairs zone only the boiler ran for over an hour there and wouldn't reach stat temp of 70! Levelled off at about 62c flow 50c return and stayed there running full time it felt like.

About 10c outside also.

So I put on upstairs smaller zone now and will let it run tonight. I'd imagine it will be just fine for upstairs but for downstairs it's clear 26kw / 0.65 nozzle is the output needed so that will go back in tomorrow and that's the end of that! 26kw it is.

 

[John.g]

A 0.6 USGPM SHOULD GIVE ~ 21kw the 0.5 is probably only 16/17 kw

 

[JC22024]

A 0.6 USGPM SHOULD GIVE ~ 21kw the 0.5 is probably only 16/17 kw

Using Danfoss Nozzle Calc spreadsheet I got the following values based on specific Firebird settings:

0.5gph / 1.5kg/hr nozzle set at 9.8bar actual pump pressure consumes 1.66 kg/hr / 2.1L/Hr / 19.92kw
0.65gph / 1.95kg/hr nozzle set at 9.3bar actual pump pressure consumes 2.81 kg/hr / 2.66L/Hr / 25.23kw

I put it back to the 0.65 nozzle this evening. I also cleaned the pump filter (I think a faulty new paper oil filter element on my oil tank caused temporary contamination) and that appears to have cured the strange popping noises on first startup.

So I guess 25.23 x 92% efficient means roughly 23.2 kw to rads? It does heat either zone well like this.

 

[JC22024]

I have had the digital BEM connected for a few days and it ain't no good. It keeps the boiler temps down all the time. Heat was on there today first run and it doesn't even let it get fully up to temp.

The Vector one was working well and crucially for me was not adversely impacting the comfort in my house. The heat felt normal as it allowed the boiler stat to fully satisfy.

So Vector will be wired in permanently today and the boiler will stay as 26kw.

Only things left is to get the rads all balanced and see what delta drop there is. I probably will not be able to get this boiler to produce condensate in my setup but I'll try that one last time also just for completeness of this thread

 

[Chuck]

I have had the digital BEM connected for a few days and it ain't no good. It keeps the boiler temps down all the time.

In my opinion, if you have a reasonably modern and correctly commissioned boiler there is little point in adding a third-party 'magic box' controller to a domestic system. Although they might have achieved the claimed savings years ago when boilers were controlled by a single thermostat, these days domestic boilers are already monitoring and controlling based a range of operating variables including flow and return temperature and have been optimised by the manufacturer. If there were "30% energy savings" to be made Worcester, Vaillant, et al. would have already modified their control strategy accordingly.

 

[JC22024]

In my opinion, if you have a reasonably modern and correctly commissioned boiler there is little point in adding a third-party 'magic box' controller to a domestic system. Although they might have achieved the claimed savings years ago when boilers were controlled by a single thermostat, these days domestic boilers are already monitoring and controlling based a range of operating variables including flow and return temperature and have been optimised by the manufacturer. If there were "30% energy savings" to be made Worcester, Vaillant, et al. would have already modified their control strategy accordingly.

Did you read this thread?

Did you look at my boiler?

It only has a stat on it NO other controls, sensors or compensations. A BEM in my case makes perfect sense.

But for modern gas boilers you are correct. It appears oil boilers have been left behind in heating advances.

 

[JC22024]

The Vector BEM unit is now permanently wired in. I used 4 core heat resistant flex. Heating call wires go to boiler stat. (Including a wire from the call positive passing through the thermostat housing).

After the stat these then go through to the Vector. It gets Earth, Call positive, stat switched positive out and neutral. Then on to the burner which means the burner also does post purge cycle except on final shutdown. I prefer the boiler to be completely isolated when turned off.



I like the Vector BEM in particular because it let's the boiler stat fully satisfy before economising. And it's got simple counters showing it is

 

[SJB060685]

I should have logged on sooner. There’s too many comments for me to scroll through everything and know what the issue/issues were but seems like an interesting thread from what little I have read.

 

[JC22024]

The Vector BEM is continuing to work very well. House feels warm and comfortable no discernible difference.

It appears to average about 15% saving downstairs zone and about 18-20% on upstairs zone which is very good in my books!!



I order my heating oil online so will be able to build up records of the last few years consumption. But so far this set up appears vastly more efficient than my old boiler. (Which you would expect I guess!)

31st Dec oil tank level:



Tonight:





My last oil order was on 30/10/21 for 900L. Looks like there is about 600 / 700L ish still in the tank. Going by oil orders for last 3x winters typically I would use 1900L per winter. With first order in Oct and last in Feb / March.

Looks like this year's 900L may just last the season. Will be interesting to see!

 

[SJB060685]

So what is this BEM controller doing exactly? An oil burner technician by trade but not familiar with the unit you mention in all honesty.

 

[JC22024]

So what is this BEM controller doing exactly? An oil burner technician by trade but not familiar with the unit you mention in all honesty.

My boiler has the bog standard stat on it. It was cycling quite a lot before the BEM. Off and on too frequently almost.

The BEM monitors the boilers firing cycles and extends them. What I like about this one in particular is that it does not interfere with the set thermostat temperature on the boiler. It let's the stat call until fully satisfied. Then when it would normally be quick to fire up again at say 5c drop in temp the stat calls but the BEM goes into economy mode and holds it back a half minute or so longer before letting it fire. Therefore less bouler cycling per hour. So less pre and post purge cycles out the flue as well.

Energy Management Solutions | Vector Group

I tested another smart BEM with delta sensors too and it was crap. It was holding the boiler back from reaching stat temperature unlike how this Vector unit operates.

I also like the simple Heating and Burn counters so you know it is doing its job.

 

[SJB060685]

Thanks for the description. You’re clearly quite well informed as a homeowner . Another thing it’s good for is as you mentioned it governs the stop/start cycling. Burners are happy running for long periods of time and ideally as cool as possible. What is not good for them is this stop start cycling. It puts a lot of wear and tear on burner components will need replacing more frequently.

 

[JC22024]

Thanks for the description. You’re clearly quite well informed as a homeowner . Another thing it’s good for is as you mentioned it governs the stop/start cycling. Burners are happy running for long periods of time and ideally as cool as possible. What is not good for them is this stop start cycling. It puts a lot of wear and tear on burner components will need replacing more frequently.

Thanks for that and yes good point on less wear and tear also!

I knew the upstairs zone was gaining more on the BEM. (I presume because the 26kw is oversized for upstairs zone and perfectly sized for larger downstairs zone)

So tonight I checked the BEM counters before and after the upstairs ran for just over 2 hours. The BEM saving in Burn time tonight was 26.7%.

That is pretty significant saving and the heating feels totally normal inside, quit early as it satisfied the room thermostat also. It was holding back the burner for up to a minute extra each cycle near the end of the 2 hours. Definitely pleased with how that is working!