Installing a whole new central heating system - options?

[Phil_D]

dont forget if one wont cover the whole system then 2 systems can be used therefore if one fails there is another

As in add an additional boiler?

 

[gaz1]

yes 2 25kw boilers will still run your system

one can be used upstairs and one used for downstairs

a thermal store can also run both systems as one system as well

https://www.stovesonline.co.uk/wood_burning_stoves/Thermal-Stores.html

dazza can also answer your question on a thermal store being used as hes got a system already

his house is concrete built and large at that

http://www.mig-welding.co.uk/forum/...inder-thats-locked.72150/page-22#post-1091713

i could throw this into the mix

https://www.ebay.co.uk/itm/central-...199292?hash=item2a9b5d253c:g:8uQAAOSwOyJX9r7g

 

[Phil_D]

yes 2 25kw boilers will still run your system

one can be used upstairs and one used for downstairs

a thermal store can also run both systems as one system as well

https://www.stovesonline.co.uk/wood_burning_stoves/Thermal-Stores.html

dazza can also answer your question on a thermal store being used as hes got a system already

his house is concrete built and large at that

http://www.mig-welding.co.uk/forum/...inder-thats-locked.72150/page-22#post-1091713

i could throw this into the mix

https://www.ebay.co.uk/itm/central-...199292?hash=item2a9b5d253c:g:8uQAAOSwOyJX9r7g

Definitely Interesting but for now I’m trying to keep things a little more straight forward.

There’s a green star heatslave 32w up for grabs for £150.. it’s a fair old drive away but probably worth it. The seller claims it’s 2-3 years old but I’m sure the heatslave 2 superceded it before then?

 

[julianf]

yes 2 25kw boilers will still run your system

one can be used upstairs and one used for downstairs

The chap really does not need 50kw to heat his 3 bed cottage! : )

 

[dazza]

yes 2 25kw boilers will still run your system

dazza can also answer your question on a thermal store being used as hes got a system already

his house is concrete built and large at that

I think the 25kw heatslave will be enough mine is 30kw running 17 rads. Although its a combi we use it to top up a solar hot water tank so the combi side is switched off. With the tank its better pressure and no dips in temp if someone runs the hot taps else where.

 

[sg66]

High kW are needed for direct hot water, you could run 2 boilers which would run half of what a single one would but it would use the same if not slightly more fuel, get as new as you can and preferably condensing as it will be more efficient.

 

[dazza]

How much more efficient at these boilers i've gone thorough 500l in two months.

 

[addjunkie]

How much more efficient at these boilers i've gone thorough 500l in two months.

Mine 30 kw and use about 500 ltrs a year but we supplement ours with wood on the back boiler. And the house though a decent size is extremely well insulated.

Sounds to me like you need lots more insulation in your house

 

[dazza]

Mine 30 kw and use about 500 ltrs a year but we supplement ours with wood on the back boiler. And the house though a decent size is extremely well insulated.

Sounds to me like you need lots more insulation in your house

I just hope its not down to my dodgy installation. Maybe the burner needs adjusting? Don't think having two thermostats helps.

Edit: Single glazing solid concrete floors and ceilings with no insulation and no carpets.

 

[mechman]

Could be a clue there.

 

[addjunkie]

Edit: Single glazing solid concrete floors and ceilings with no insulation and no carpets.

Were 100 mm kingspan in the floor, underfloor heating, 50 mm all outsidewalls, 200mm in most of the roof, 150 in dormers. A rated windows.

 

[Phil_D]

Well the heatslave 2 I saw on eBay literally sold instantly so no luck there, it was 25kw so may have been a tad on the small side

 

[julianf]

re: boiler sizing -

you have the quote from the company, right? what size unit did they spec for?
also, you have a list of the rads that they were going to install?

if you total up the output of the rads, and the hot tank, that should match up with the boiler.


Theres very little point in having some massive boiler if the rads you have it connected to can not dissipate that heat - all that will happen is that the boiler has to cycle all the time, which, in itself, is not a great idea. Or you run the coolant so hot in an attempt to shed the heat that the return is way above the distillate temp of water anyhow, so youre never in condensing mode, and you drop efficiency that way.

What im saying is bigger isnt just better - you want the boiler matched to the tank and rads. Sure, there may be a minor advantage in having a larger exchanger, and then jetting down the burner, but my advice is to try not to get sucked into thinking you need some vast monster.

 

[gaz1]

measure your rooms and calculate your rads btu

its better to have a rad slightly oversized than under sized and the room feels cold

 

[Phil_D]

re: boiler sizing -

you have the quote from the company, right? what size unit did they spec for?
also, you have a list of the rads that they were going to install?

if you total up the output of the rads, and the hot tank, that should match up with the boiler.


Theres very little point in having some massive boiler if the rads you have it connected to can not dissipate that heat - all that will happen is that the boiler has to cycle all the time, which, in itself, is not a great idea. Or you run the coolant so hot in an attempt to shed the heat that the return is way above the distillate temp of water anyhow, so youre never in condensing mode, and you drop efficiency that way.

What im saying is bigger isnt just better - you want the boiler matched to the tank and rads. Sure, there may be a minor advantage in having a larger exchanger, and then jetting down the burner, but my advice is to try not to get sucked into thinking you need some vast monster.

Totally get where you’re coming from mate but the quote was vague and I didn’t manage to get hold of him today to clarify various things. No mention of boiler models, rad sizes etc..

In case you needed a good laugh:

 

[Phil_D]

measure your rooms and calculate your rads btu

its better to have a rad slightly oversized than under sized and the room feels cold

Did that earlier and results varied wildly depending on what calculator I used. One gave me a range of 44175-53025 BTU and another was 36785 BTU

The 25kw ones tend to pump out 85000BTU max, so maybe that would be plentiful for ,y heating and hot water.

 

[julianf]

Theres some extra stuff on there like the gas stuff, trench digging, and nice stuff like saying all underfloor pipe will be copper - which isnt required,but is a better job. Still a fair bit of margin, but you can at least see where some of the money is going.

 

[wookie]

How much more efficient at these boilers i've gone thorough 500l in two months.

Ouch!

How do you get through 500L in 2 months ? is your place huge or do you like it tropical 24/7 ?

I live in an old welsh cottage, because we wanted to keep the character we have slate floors & stone walls that aren't insulated, we've managed a little insulation in the roof and have double glazed windows. 1000L of oil usually lasts us 9 to 10 months including the winter and that's with a conventional non-condensing boiler.

 

[dazza]

Ouch!
I live in an old welsh cottage, because we wanted to keep the character we have slate floors & stone walls that aren't insulated, we've managed a little insulation in the roof and have double glazed windows. 1000L of oil usually lasts us 9 to 10 months including the winter and that's with a conventional non-condensing boiler.

How do you get through 500L in 2 months ? is your place huge or do you like it tropical 24/7 ?

Its 200m2 the boiler is on for an hour in the morning and 2/3 hrs in the evening. Not seen the temp get above 20º even after being on for hours. Usually 18 to 20º. If the boiler uses 3L an hour thats about right no?

 

[gaz1]

use this one

https://www.mrcentralheating.co.uk/btu-calculator

also using this info

http://www.directheatingsupplies.co.uk/news/btu-calculator-how-to-work-out-what-radiator-you-need/

so using the above get your desired btu then using the other add or delete

For solid floor -10%

the other calculator only calculates room size and if its sheltered or exposed it dosnt include window sizes

go here for size of rads most places stock stelrad including ebay

http://www.directheatingsupplies.co.uk/stelrad-vita-compact-radiators