System Boiler or Combi-boiler

mrsmsebastian

Hi all,
We moved in a property that only has electric heating. Right from the start I knew I need to have gas heating but I am not sure what to choose now between combi and system boiler. Originally I am convinced I wanted a system boiler as I dont want the water pressure/temperature affected when someone in the house open the kitchen tap.
Currently we have water heating tank and a water reservoir in the loft and the pressure/temperature in the shower is always consistent but since I am upgrading our heating system, I thought system boiler can deliver the same effect but someone posted here that the problem with it is you need to heat the whole tank every time you need to use hot water.
Can you please advice me on what to choose suitable for our house? It is a 3 bedroom bungalow house with just one shower room and we are 5 in the house. I have to consider my 3 kids will grow up and probably extend to have another shower room.
Would a combi-boiler suitable when two taps running (or two shower)? Will it not affect the water/shower pressure and temperature?
Your advice will be appreciated.

tacpot12

I would go with a system boiler. Note that what you need is actually an open vent boiler because you have a tank in the loft. System boilers would normally be used with a pressured hot water tank. These deliver hot water at the same pressure as cold water, but need to be inspected/service every year so are much more expensive than the system you currently have. 
I had my open vent boiler replaced last year with an Intergas HRE OV boiler and have been very pleased with it so far.

mrsmsebastian

tacpot12 said:

I would go with a system boiler. Note that what you need is actually an open vent boiler because you have a tank in the loft. System boilers would normally be used with a pressured hot water tank. These deliver hot water at the same pressure as cold water, but need to be inspected/service every year so are much more expensive than the system you currently have. 
I had my open vent boiler replaced last year with an Intergas HRE OV boiler and have been very pleased with it so far.

Thanks for the reply. 
The water tank in the loft is not needed in system boiler is it? So I am hoping it will be removed and only water heating tank will be left but if the system boiler is much exoensive to run then shall I go with combi-boiler?
The only thing I am concerned with combi-boiler is the water pressure and temperature if multiple taps is being used at the same time.

theoretica

Combi boilers can only heat so much water at a time, so when you turn a second tap on the flow from the first will probably reduce, but a larger combi boiler and low flow showers might be a solution for you.  A system boiler tank is only so large so several showers in a row/at once and the last people could have cold water - probably the case with your current system and will depend on if you are changing the size of your tank or not.

RelievedSheff

Having gone from a system boiler to a combi I much prefer the combi with hot water on demand rather then having to wait for it.

If you do add another shower room you could always install an electric shower to reduce the demands from the combi boiler of both showers are used at the same time.

EssexExile

Don't worry about having to heat the whole tank to get some hot water. Once heated it will stay hot all day, or until you use it.

FreeBear

EssexExile said: Don't worry about having to heat the whole tank to get some hot water. Once heated it will stay hot all day, or until you use it.

I have a system boiler plus a reasonably well insulated  HW tank (Baxi back boiler) - To heat a full tank takes around an hour. To keep a tank heated all day uses around an hour's worth of gas depending on HW usage. Most days during the summer, it isn't worth it just to have hot water for washing up and washing hands. Much cheaper and energy efficient to boil water in a kettle.

If/when the Baxi gets to the stage of "beyond economical repair", I'll rip it out and stick a combi in.

Rosa_Damascena

EssexExile said:

Don't worry about having to heat the whole tank to get some hot water. Once heated it will stay hot all day, or until you use it.

Nor low water pressure to multiple showers, that's easily solved with individual pumps.

mrsmsebastian

EssexExile said:

Don't worry about having to heat the whole tank to get some hot water. Once heated it will stay hot all day, or until you use it.

Really!? That is good but will the boiler automatically turns off after the water is heated or will it stay on to keep the water hot?
Apologies for too many questions. I would rather know something before the boiler man comes so I can tell him what I want which will be suitable in our house.
Thank you for your help!

theoretica

mrsmsebastian said:

EssexExile said:

Don't worry about having to heat the whole tank to get some hot water. Once heated it will stay hot all day, or until you use it.

Really!? That is good but will the boiler automatically turns off after the water is heated or will it stay on to keep the water hot?
Apologies for too many questions. I would rather know something before the boiler man comes so I can tell him what I want which will be suitable in our house.
Thank you for your help!

I suspect, like combi boilers, it will depend on how sophisticated a management system you pay for! 

Rosa_Damascena

mrsmsebastian said:

EssexExile said:

Don't worry about having to heat the whole tank to get some hot water. Once heated it will stay hot all day, or until you use it.

Really!? That is good but will the boiler automatically turns off after the water is heated or will it stay on to keep the water hot?
Apologies for too many questions. I would rather know something before the boiler man comes so I can tell him what I want which will be suitable in our house.
Thank you for your help!

If it remains switched on, it stays hot until the temperature drops and then it kicks in again. I have my boiler heating the water for 10 mins in the morning and its stays hot until I have another wash before bed.