Efficency of my Boiler

[GARYDAVISON]

HI .
Ive read your forum for many years,so much so that in my previous house i bought a Viessmann w 100,after moving into a Places for people property{yeah divorce and she gets the house ive got a new boiler and have had massive gas bills ie £165 for a month,now i know gas and lec is dear but i thougth id run my boiler etc past you guys and you could advise me how efficient it is.
The boiler is a GLOW WORM 18hxi so its a combi i believe,however rather than the Viessmann tht supplied hot on demand this one has a huge copper foam clad storage in my sons bedroom ie behind the boiler???it also has an immersion element that ive turned of and on the side of boiler {FOAM COOPER}is a HONEYWELL L641A1039 I ASSUME THIS IS A TEMP SENSOR CONNECTED TO THE BOILER IVE SET IT AT 70,
Ive also noticed a right angle pipe with what looks like a bleed screw on the side of boiler.
Idid have proggramer {Danfoss FP715 Si }set at allday.the central heating went of at night .
I now have the water turned off until i need it as i believe holding water in the large boiler is costing me money
At a guess{ive tried to helpmyself before writing}this is a "system boiler with a combi.
right sorry for the long post but if this setup is grossly wrong for my property ie 2 bed terrace with 1 guy in} i will ask for an n ew system as it looks very old.
Thanks for reading and sorry no photo as my wife has all my stuff in the FHM.
CHEERS.

 

[Dan Robinson]

It's not a combi.

It is a heat only boiler.

Set the Glow-worm to 3/4, and the cylinder to somewhere between 50 and 60.

Changing to a combi is probably not necessary, but the hxi isn't the most efficient boiler out there due to its poor turndown ratio (it'll be constantly be cycling on and off.

 

[DP]

You do not have a combi boiler.

Reduce he cylinder setting to 55

Put the HW setting to twice a day to start say about 30 minutes prior to use of hot water. Having said that, loss from the cylinder will be minimal bu her is no mileage in preserving 55 degrees all day if no one at home

Instal a programmable room thermostat to control boiler

 

[ALEC1]

how big is the house....A figure I heard that the average three bed house is costing £3.50 to £4.50 a day to heat this winter...thats from BG who supply my gas...

 

[GARYDAVISON]

Wow thanks for the quick info
Ok ill try and answer quries.
Iwas told system was a combi by the gas guy but im inclined to believe you guys.
IMretired from fire service so in all day i have a room thermosta and have it set to 15. its a honeywell{situated in my hall.
Thanks for info on temps now set to 55.{i hope you meant the glow worm?}
the system was fitted with MAGNACLEAN,about 2 months ago as downstairs rads werent heating up ,was told they adjusted the BALANCE and put on magna clean after flushing ,the rads are fine just the pump sounds lloud and transfers sound through house ,
IVE also set the copper boiler ie surrou8nded by foam to 50 ,and am just going to put hot water on 30 mins before i need it.
I live in a 2 bed normal sized home and am in most days
Thanks again for reply feel free to add anything i might have missed
Just to clarify the honeywell sensor {not room thermostat}is on the side of the copper cylinder.

 

[Dan Robinson]

The boiler (Glow Worm) should be set to about 3/4 of maximum.

The cylinder (with the Honeywell) should be set around 55.

It is NOT a combination boiler. It is a condensing heat only boiler.

Hence the separate hot water cylinder and pump.

You house probably only uses 6kW or less of energy (when it is sub zero outside). The boilers absolute minimum output (not that you have much control over that is 5kW); which is actually a little lower than I remembered.


IF a gas guy told you it is a combination boiler then he is a total ********. Get a different gas guy.

Are you sure you are not mixing up the word "condensing" with "combi"? Lots of people do.

 

[JBPHS]

Setting Hot Water cylinder stat to 55°C? Have I missed the Regs about this changing? Anyone who works in the industry and has the relevant qualifications for stored domestic hot water should not be recommending less than 60°C for stored hot water.

As said above, you've got a condensing heat only (pump is external) boiler. Combination boilers provide heating and hot water direct from the boiler itself (I.e. No hot water cylinder). The maximum setting on the boiler is around 82°C, I'd be looking to set this at around 65-70°C so it doesn't run all the time when turned on for hot water.

Try to keep the water in the cylinder hot, more energy is used re-heating from cold than to tick over maintaining the it at around 60°C. Larger volumes of water hold their heat longer. Usually best to run hot water on continuous or at least all day. This is a similar reason why programmable room stats that allow different temp settings (rather than on/off, on/off timings) are more efficient if used correctly.

Best thing to do is insulate pipework, walls, etc. minimise on heat loss as much as possible.

James.

 

[Dan Robinson]

Setting Hot Water cylinder stat to 55°C? Have I missed the Regs about this changing? Anyone who works in the industry and has the relevant qualifications for stored domestic hot water should not be recommending less than 60°C for stored hot water.

Hysteresis ? .

Besides, the bottom of the cylinder ill never get to 60. My cylinder regularly overshoots by 6 or 7 degrees. Set temp is 57, boiler flow is 65.

And yes; those figures are very precise.

 

[ALEC1]

Legionella is a risk, but how many recorded cases are there with a hot water cylinder as the source?

I suspect that as the primaries are usually significantly higher than set temp the water may be sanitised..

Vaillants controls reheat at 80c by default, and even have anti legionella programmes enabling you to store water as low as you like..

 

[GARYDAVISON]

yes im probably getting confused,going from a viessmann brand new too this ungainly boiler takes some getting used to{saying that the viessmann went wrong but that was the fitters fault as condensate pipe had no incline.
Best thing i can do is use system and put in monthly meter readings.
Happy New Year