banking boilers

Idbatterim

hi, what is the reason for banking say 2 or 3 boilers together, as opposed to just putting in one bigger kw boiler?

shane0007

It has a number of advantages. Namely required kw output as zones open or close. For example, a commercial 4 storey building might only have 2 floors calling heat, so some of the boilers are off, only coming on to meet the larger demand when other floor request.
Other reasons include breakdowns. If one large boiler goes down you have no heat. If one of 3 boilers goes down, you still have 66% power.

Idbatterim

It has a number of advantages. Namely required kw output as zones open or close. For example, a commercial 4 storey building might only have 2 floors calling heat, so some of the boilers are off, only coming on to meet the larger demand when other floor request.
Other reasons include breakdowns. If one large boiler goes down you have no heat. If one of 3 boilers goes down, you still have 66% power.

I get the bit about zones being closed, but cant automatic valves to this? so the boiler wouldnt be heating water unnecessarily? Or will a 100kw boiler always use the same amount of gas or oil etc even if only heating half the water for rads?

shane0007

Do you mean zone valves by automatic valves?
Lets take a 3 storey building with a demand of 30kw per floor, total 90kw. Each floor valve calls in a particular boiler or to a control centre that has the boilers react to return temperature, either way is common. The boilers then use the amount of gas required.
On the other hand, a 90kw boiler will give full throttle on cold start up even for just one zone and modulate down as the return temp increases.
The difference in fuel usage will be marginal but other factors in design usually win over to determine the end product used.
Why do you ask?

Outkast_IRE

Idbatterim wrote: »

I get the bit about zones being closed, but cant automatic valves to this? so the boiler wouldnt be heating water unnecessarily? Or will a 100kw boiler always use the same amount of gas or oil etc even if only heating half the water for rads?

Zones can be controled by actuator valves in any type of setup, thats more to do with system design rather than boiler specification.

As to will a 100kw boiler always use the same amount of gas the answer is it depends on the boiler , some modern boilers can modulate themselves depending on the heat load being required of it at any given time however there is a strong argument for my following statement

" generally older boilers will operate at their best efficiency when under full load conditions, as there will be less on/off cycling................ modern boilers by their very nature are high efficiency condensing boilers and for them to operate at maximum efficiency it is often best design wise that the return temperature of the water is lower to aid the efficiencies gained by the condensing effect, for this to happen most efficiently, boilers should be matched with the load as much as possible at all times. The best way to match with load to achieve a consistent return temperature is boilers in parallel and each one capable of its own modulation. This will especially ring true in autumn and spring seasons when the heating load on the building can vary greatly on a daily basis depending on outside weather conditions."

that was a mouthful off to bed soon i think

Idbatterim

thanks for the replies, asking cause my parents have 4 story former small hotel, roughly 10,000 sq foot, 4,000 sq foot basement and then ground floor, 1st and 2nd floor are roughly 2000 sq foot each. basement is function room, bar and other few smallish rooms. Ground floor has reception area, small office, lounge, large dining room and fairly large kitchen. Top 2 floors are bedrooms, so thinking might be best to have 2 boilers? one for basement and ground level and one for accomodation... and then have automatic valves between each floor, so can zone then. Then extra valve in basement so can seperate the 140 sqm function room from rest of basement. Its not connected to mains gas, so question is oil, lpg or wood gasification. My dad already has a huge amount of wood. But they seem to be at least double the cost of lpg boiler for same kw output, and also require accumulator tanks which arent cheap...

Outkast_IRE

Idbatterim wrote: »

thanks for the replies, asking cause my parents have 4 story former small hotel, roughly 10,000 sq foot, 4,000 sq foot basement and then ground floor, 1st and 2nd floor are roughly 2000 sq foot each. basement is function room, bar and other few smallish rooms. Ground floor has reception area, small office, lounge, large dining room and fairly large kitchen. Top 2 floors are bedrooms, so thinking might be best to have 2 boilers? one for basement and ground level and one for accomodation... and then have automatic valves between each floor, so can zone then. Then extra valve in basement so can seperate the 140 sqm function room from rest of basement. Its not connected to mains gas, so question is oil, lpg or wood gasification. My dad already has a huge amount of wood. But they seem to be at least double the cost of lpg boiler for same kw output, and also require accumulator tanks which arent cheap...

To be honest its the sort of size job where someone should design the system properly and not just go on internet advice.

My opinion if its going to operate as a hotel you need to have more than one boiler and ideally have them in a the same location and have the system designed so they are both capable of heating all areas if needs be.

In that type of business between hot water demand and heating, you cant rely on a single boiler you need redundancy in case one develops a fault ...... guest wont be happy if theres no hot water for showers etc.

As for oil, lpg or wood gasification ......... yes wood gasification would require accumulator tank and a constant supply of quality wood , that would depend on your own circumstances , some people have access to large quantities of quality wood.
Oil or lpg depends on where you are and what prices you would be paying, the advantage of lpg in your situation is that it cant be stolen.

But once again i have to say for this type of installation you need someone to do the homework and design this out and they should be able to give you costings .

Also it depends on how much you want to spend alot of the system design will come down to what your willing to spend for example i could design a system so every individual room has its own thermostat so they can control their own heating (EXPENSIVE but best comfort for occupants) or you just heat the entire floor and maybe use TRVS or similar as your control. Theres so many things you could do its crazy, it all comes down to what the client priorites are and budget.

Best of luck.

shane0007

Idbatterim wrote: »

thanks for the replies, asking cause my parents have 4 story former small hotel, roughly 10,000 sq foot, 4,000 sq foot basement and then ground floor, 1st and 2nd floor are roughly 2000 sq foot each. basement is function room, bar and other few smallish rooms. Ground floor has reception area, small office, lounge, large dining room and fairly large kitchen. Top 2 floors are bedrooms, so thinking might be best to have 2 boilers? one for basement and ground level and one for accomodation... and then have automatic valves between each floor, so can zone then. Then extra valve in basement so can seperate the 140 sqm function room from rest of basement. Its not connected to mains gas, so question is oil, lpg or wood gasification. My dad already has a huge amount of wood. But they seem to be at least double the cost of lpg boiler for same kw output, and also require accumulator tanks which arent cheap...

Something of this type of installation is not guess work. It must be calculated based upon the realms of the existing installation. IMO, I would certainly not entertain oil, unless it is going into a buffer tank. Reaon: oil boilers themselves cannot modulate unless you go for very expensive. You can, of course, get two & three stage burners. Not modulation but better than single stage as it is tiered output.
I would seriously consider commercial rate LPG. Many hotels & hospitals are on LPG. You have the benfit of pure modulation.
Regarding wood gasification, I do not know enough about them to give informed advice, so perhaps more knowledge chappies could input on their capabilities.

Idbatterim

thanks for the detailed replies outkast and shane. Will contact calor tomorrow to find out more about lpg pricing, we already have lpg on site to heat an apartment located in the house, its a small tank and calor are the providers...

To be honest its the sort of size job where someone should design the system properly and not just go on internet advice.

agreed but I want to inform myself as much as possible.

In that type of business between hot water demand and heating, you cant rely on a single boiler you need redundancy in case one develops a fault ...... guest wont be happy if theres no hot water for showers etc.

we are considering for guest rooms, the possibility of just electric showers, say we have 10 bedrooms per floor, the problem is the vast majority of times showers arent in use, then you might get a fri and sat evening or sun morning when everyone wants to use them at same time and you have to have massive redundancy for this.

Also it depends on how much you want to spend alot of the system design will come down to what your willing to spend for example i could design a system so every individual room has its own thermostat so they can control their own heating (EXPENSIVE but best comfort for occupants) or you just heat the entire floor and maybe use TRVS or similar as your control. Theres so many things you could do its crazy, it all comes down to what the client priorites are and budget.[/QUOTE money is a big factor, we want the basics right from the beginning though,probably put in trvs in each bedroom...

shane0007

Don't go by pricing over the phone as they will not do deals over the phone. Get the number of the rep for your area & arrange a site meeting. Discuss then, always playing your hand close to your chest. Mention your options other than Calor. Mention their competitors. Mention other fuel options you are considering.

jjf1974

Idbatterim wrote: »

[ we are considering for guest rooms, the possibility of just electric showers, say we have 10 bedrooms per floor, the problem is the vast majority of times showers arent in use, then you might get a fri and sat evening or sun morning when everyone wants to use them at same time and you have to have massive redundancy]

You wont be able to power that many electric showers on your electric supply as they use 9kw each.

Idbatterim

You wont be able to power that many electric showers on your electric supply as they use 9kw each.

even if its a 3 phase supply?

slavetothegrind

Idbatterim wrote: »

even if its a 3 phase supply?

yes, each shower will pull approx 37 amps on a phase so if you had 2 per phase totalling six you would be overloading the building supply right there not even allowing for a lightbulb being on!

non runner

you may have significant other electrical demand in the kitchen to consider etc.

your heating designer will calculate the max potential hot water demand and decide from there how to supply it

Idbatterim

no worries, will just put in one or two then possibly (have seen some 7.5kw ones), so if only one or two rooms in use, can just use them, any more and we can turn on water boiler and work out best way to run it, i.e electric, gas etc...

shane0007

Idbatterim wrote: »

no worries, will just put in one or two then possibly (have seen some 7.5kw ones), so if only one or two rooms in use, can just use them, any more and we can turn on water boiler and work out best way to run it, i.e electric, gas etc...

I would forget about domestic showers for a hotel. Many other options more suited to hotels are available.
Most certainly instantaneous gas water heaters for a commercial kitchen.