System or Regular boiler

[BlueLoo]

What are the pros for open vented in this case ?

Why fit a sealed system with a system boiler? is the question.

Unless you are living in a flat, i can't see an obvious answer.

 

[BlueLoo]

1. You can have a sealed system on an open vented boiler, provided the boiler MI's says its OK. Most do.
2. On the sealed v. open vented debate, I prefer sealed. Because:
2.1 The only extra things to go wrong in the long run are the expansion vessel and pressure gauge. In my opinion this outweighs the chances of air causing corrosion if the inhibitor is not maintained.
2.2 You can get rid of the F&E tank, and its normal collection of nasty gunk waiting to be washed into the pipework.

Considering this myself atm because of air in the system.

 

[MNW67]

So from my POV it wouldn't matter.

What if somebody wanted to run their heating cool but still have the cylinder hot?

 

[JohnD]

You mean HW above, say, 60C?

My rads mostly run cooler than that because they are oversized, and the digital Wall stat notices the room temp creeping up before the rads get to 80C

If you want cool heating, you need big rads.

 

[MNW67]

Say heating at 50 to maximize condensing and HW at 55

 

[BlueLoo]

Say heating at 50 to maximize condensing and HW at 55

X plan?

 

[MNW67]

X plan?

We're debating pros and cons of X-plan!

At least I think we are!!

 

[BlueLoo]

 

[akist]

Say heating at 50 to maximize condensing and HW at 55

I have a feeling the "cool radiator" idea maybe suspect.

Anyway in my system I want *at least* 65C water, as I already have experienced contamination with lower temps and a megaflo, so I will ask the installer to set flow temps to something suitable, eg 65C-70C or more.

Or maybe there is a way to allow the boiler to operate smartly in two modes, a low 50C flow and a full heat flow, based on rules, eg difference of ambient temp to room thermostat setting, or Hot Water demand ?

 

[MNW67]

I have a feeling the "cool radiator" idea maybe suspect.

There is load compensation, which varies the flow temperature depending on the temperature difference between room thermostat and ambient. Open Therm is one version of that. Not all boilers can do it, though. Then there is priority hot water (aka X-Plan), where you have one flow temperature for central heating and another for hot water. Again, not all boilers can do it. Is this a replacement boiler for an older system? Radiators on an older system may be too small to give out enough heat at a low flow temperature. I think the science behind condensing is sound - in theory.

 

[akist]

Is this a replacement boiler for an older system?

No, brand new system, so we can do what we like. Will ask if the Worcester Regular Boiler can automatically put out top heat if there is a large difference between thermostat and ambient, or if hot water is needed. Or maybe it does it on the difference in temperature between flow and return. Will send them an email now.

I think the science behind condensing is sound - in theory.

The best way to heat a room is with a very hot convection radiator because air flow depends on the radiator being very, very hot. Unless you use a fan to help with air flow, which is what I have read Daikin have done for their "cool" radiators (Daikin Altherma HPC).

While it may be "cheaper" to run the boiler at 50C, it is not cheaper if it has to run for longer, and the inconvenience for waiting until the rooms have reached temperature. Is my thinking.

 

[BlueLoo]

No, brand new system, so we can do what we like. Will ask if the Worcester Regular Boiler can automatically put out top heat if there is a large difference between thermostat and ambient, or if hot water is needed. Or maybe it does it on the difference in temperature between flow and return. Will send them an email now.


The best way to heat a room is with a very hot convection radiator because air flow depends on the radiator being very, very hot. Unless you use a fan to help with air flow, which is what I have read Daikin have done for their "cool" radiators (Daikin Altherma HPC).

While it may be "cheaper" to run the boiler at 50C, it is not cheaper if it has to run for longer, and the inconvenience for waiting until the rooms have reached temperature. Is my thinking.

There are some quite good articles on the efficiency falicy of condensing boilers. I went down that rabbit hole a few years ago but quickly came to the conclusion that replacing my std non condensing boiler for efficiency savings would never recoup the payback.
This was before the recent energy crisis so i dunno if that rings true.

My current plan is hoping it lasts out a few more years until Heat pump tech matures enough to replace it.

 

[MNW67]

No, brand new system, so we can do what we like. Will ask if the Worcester Regular Boiler can automatically put out top heat if there is a large difference between thermostat and ambient, or if hot water is needed. Or maybe it does it on the difference in temperature between flow and return. Will send them an email now.

I am not an expert! But I have heard that to make both of these things work on Worcester Bosch, you need to use their proprietary controls. A table is below. I would not just rely on the literature, though. Get everything confirmed by email. There can be mistakes in this sort of literature. I have also been told by WB that you cannot do priority hot water at all with the regular boiler. You can do it with the system boiler, but only by using the optional internal diverter kit. It looks from the table that you cannot do load compensation with the regular boiler either. I think you need to use Sense I for that, and it doesn't seem to be compatible with the regular boiler. Sense II is for weather compensation which varies the flow temperature depending on outdoor temperature. My knowledge of these WB controls is gleaned from the brochure. I am not an expert on WB! Other boiler brands are available which are more open to third party controls.

EDIT!!!!! Some of the Comfort+ range of controls may also do load compensation.

Gas Consumer Brochure | Worcester Bosch

central heating boilers, combi boilers, gas boilers, oil boilers, gas central heating, heating engineers, boiler installation, boiler repair

www.worcester-bosch.co.uk

 

[MNW67]

There are some quite good articles on the efficiency falicy of condensing boilers. I went down that rabbit hole a few years ago but quickly came to the conclusion that replacing my std non condensing boiler for efficiency savings would never recoup the payback.

I think of the condensing gains as a potential cherry on the top. The bigger gains come from other efficiency improvements. A brand new boiler is 20% more efficient than a 35 year old boiler, even if it never condenses at all.

 

[BlueLoo]

I think of the condensing gains as a potential cherry on the top. The bigger gains come from other efficiency improvements. A brand new boiler is 20% more efficient than a 35 year old boiler, even if it never condenses at all.

What's the term, SEB?

In effect, efficiency is measured (or recorded) in the optimum state. For condensing boilers, this is seemingly a bit tighter than non condensing.

It's the modulation and temperature compensation that i would think be a major benefit in my situation.

I read that most condensing boilers installed or running today are actually operating in a non condensing state because of the job-knock boiler flippers who install them and leave the rest to the gods.

If i am to get a new boiler, I'll be doing heavy research and redesign the system from the ground up to take best advantage of the tech.