Which boiler system? So confusing, Please so advice appreciated

[Holly2011]

I am updating my house and thought I would use the opportunity to upgrade my central heating system.

What I have currently
Our house is a 3 storey (ground floor, 1st, 2nd floor) Victorian house which is very cold if the central heating is switched off. 4 of us live in the house and there is 1 bathroom and 1 cloak room (on the 1st floor), we tend to have baths or use a shower tap mixer connected to the bath taps & 12 raidiators. We have tanks in the loft which serve the boiler and central heating. No plans for a 2nd bathroom for now but if we did do in the future we would like a loft conversion with a bathroom.

On the 2nd floor we have the pump and controls, timer to the central heating, on the ground floor is the kitchen which the boiler is located. In the airing cupboard in the kitchen is an immersion cylinder, which we use on an adhoc basis if the central heating and boiler is switched off and we need a quick bath in the middle of the day or very early morning. (It was also a god send when the boiler broke down at xmas but we were still able to get hot water.) I was not sure if this set up is called vented or unvented?

What I am really confused on is what type of boiler system to upgrade to?
I want to make more space in the kitchen and this would mean demolishing the existing airing cupboard and re-locating the cylinder. I would keep the boiler location in the same place in the kitchen. I was going to keep the cylinder (it's the copper encased in some kind of green material on the outside) and ask to get it re-located under the stairs so we could still rely on it if we wanted hot wanted at odd times and then replace the boiler with a condensing boiler. I also have low water pressure coming into my house checked by British Gas .

Why keep this set up?
I don’t know? I have had 3 quotes:
1-I had one heating engineer advise to keep the cylinder, water tank set up and I had also read on some post online that this traditional set up was reliable. He said he could move the cyliner to under the stairs and recco a Valliant eco Tec Plus 630 condensing system boiler replacement.

2-I have my builder and one other plumber say to get rid of the tanks and cylinder and install a (Wostercher Bosh) combi boiler as I would get more space.
However, I explained that I have low pressure and the builder said he could check the lead pipe coming into the house and get it changed if required to bring more water pressure into the house. Most of the other plumbers get really excited and straight away say combi and say go with that. However, one thing I am concerned about are there any downfalls to moving to a combi boiler set up as if I remove the tanks and cylinder (which I have had for over 20yrs with no problems) there would be no going back. My mum in law got a combi set up removing the tanks & cyliner and we have noticed at her house if someone is washing and you try to run a bath the bath tap runs very low and the bath is filled with cold water (they only have 1 bathroom no shower & 2 toilets). I would hate this to happen in our house. If the boiler broke down in this setup would that mean I would have no emergency hot water backup??

Another builder mentioned addind a pump to a combi to make it pressurised but I just did not understand this. Would be grateful if somone could explain.

It just seems that there are so many options

What is the best type of set up or am I being too cautious
I read that the Rehema Broag is a good boiler for low pressure but can’t find any experienced installer in North London, so may have to go with Valliant.

 

[GQuigley67]

the annoying thing about combi's is there is no stored hot water, I have 4 people in my house if I'm in the shower and someone runs the hot tap downstairs my shower goes freezing, so If there are alot of people in the house and your planning on having 2 bathrooms then a Combi isn't recommended in my opinion.

I would say keep the cylinder and install a system boiler due to the low pressure, if you get the low pressure sorted then upgrade to an unvented cylinder and you can get rid of all tanks, which gives you more room in loft for your bathroom or whatever and you'll have mains balanced pressure at all outlets that is if you get the low pressure sorted though.

 

[Reg Man]

If you have low water pressure don't even consider a combi or unvented, keep what works. Upgrade your boiler to a vaillant is a good move forward also look at your exsisting controls and see if they can be improved. Biggest saver is ensuring your roof space is adequately insulated.

 

[franky]

if your going to go for a combi go for a vailant 930 at least you have some stored water then.
If I was doing the system I'd keep the old tank etc at least you have a back up and the hot water doesn't fluctuate.
I think what they are saying with pumping the combi is adding on a pump from your tank in the loft which feeds the combi and so give you the mains pressure you need. But if you were to do this you might as well go the whole hog and get an unvented cylinder.
You are not allowed to add a pump directly onto the mains pipe so make sure they don't do this.
Sorry I haven't really cleared anything up for you but at least the two boilers your going for are good makes

 

[GQuigley67]

I think the pump for the combi would be a bad idea and wouldnt recommend it, as I said earlier if you sort the low pressure problem then go unvented, but it may cost a small fortune to fix and may not be fixable, so may just have to opt for existing cylinder and the new vaillant system boiler.

 

[Bartdude]

It may be possible to upgrade your water main to provide the house with good pressure and flow,this would enable you to have an unvented cylinder as already suggested,that would be the best option. It depends on the potential of the water mains in your area though. Did any of your plumbers check the pressure and flow when they inspected the job?

Failing that I would stick with your existing set up,you could increase the size of the cylinder if you feel you need more hot water,and have the cold water storage cistern checked to make sure it's clean and up to standard,many aren't.

Don't consider a combi,it's not suitable for your situation.

 

[dontknowitall]

I'm one of the old fashioned ones that doesn't like combi boilers. They have their use, but for years a cold tank (cistern) in the loft, hot water cylinder in airing cupboard and boiler downstairs has worked really well (vented system) and these systems are well proven.

If the boiler fails you can heat the hot water cylinder with the immersion heater and if the water mains has a problem you have a good 2-3 days of cold water supply.

With a combi, you lose both these storages and you get the problem of cold water when someone else is using a hot tap as described above. To me, as long as the water pressure/flow is satisfactory, the only place combi's come into their own is in small dwellings where space is at a premium.

I freely admit that I'm biased against combis!

 

[GQuigley67]

easy to fit, but have there disadvantages especially with family homes