Combi v System for 4 bedroom house

[RobGra]

I've read previous threads on this, both in here and elsewhere, but opinions seems to be varied. Could I ask for opinions on my specific circumstances:

I've a 4 bedroom house, with bath and en-suite shower, currently serviced by a Potterton Promax FSB HE, 30Kw. It's given me problems over the years, but I've limped on with it, however, now, if I turn the boiler thermostat above say 1/3rd, the boiler is tripping out on overheat. I've had engineers look at it, who have replaced stats, thermistors, etc. But the problem persists. The pipes and system are pretty clean, and there's never a lot of accumulation in the Magnaclean.
So I've decided to cuty loses and get new boiler.
It's only me and Mrs in house now, & we don't really need to worry about using hot water (like shower or bath etc) at same time, and as our upstairs CW supply is from the header tank, I like the idea of fresh water in the bathrooms. I've a pump driven power shower in the en-suite too. As my water pressure is very good, I was leaning towards a combi with sufficient output, however, I've been put off by some comments against larger houses having combi boilers etc.
I'm considering the Worcester Bosch Style 35Kw, but I'm not yet 100% convinced on a combi
Before I start to get quotes, I would appreciate some opinions on this please?

Thank you

 

[pcaouolte]

In my (DIY) opinion if you already have stored hot water then keep it. I find that combi boilers are more trouble than system boilers.

 

[Mister Banks]

I'm no expert on these things but IMO you should get a boiler that is compatible with the house rather than the occupiers which from what I have read online means a combi is not an option. Plenty of experienced people on this site so will be interesting to know what they think.

 

[oldbutnotdead]

As above, if you have hot water storage then keep it, it insulates you from external changes (combi or unvented cylinders are great til the local water supply drops to USO cos a new housing estate goes up).

 

[vulcancontinental]

The boiler should suit the user not the house in my opinion but if you go the combi route think about proximity of DHW to outlets to source. Also think about the implications of reusing old gravity domestic pipework on a combi, it’ll be too large a bore leading to wastage and delay. If cylinder is new keep it, it will be well insulated, if not a combi might be something to consider. Too many unknowns for a forum, find an experience plumber to advise and take time to weigh up options.

 

[Mister Banks]

The boiler should suit the user not the house in my opinion but if you go the combi route think about proximity of DHW to outlets to source. Also think about the implications of reusing old gravity domestic pipework on a combi, it’ll be too large a bore leading to wastage and delay. If cylinder is new keep it, it will be well insulated, if not a combi might be something to consider. Too many unknowns for a forum, find an experience plumber to advise and take time to weigh up options.

Surely if you install a boiler in a 4 bedroom, 3 bathroom house with just 2 people living there then sell the house to a family of 6 don't you want the boiler to be suitable?

 

[vulcancontinental]

Surely if you install a boiler in a 4 bedroom, 3 bathroom house with just 2 people living there then sell the house to a family of 6 don't you want the boiler to be suitable?

If someone wants a house they'll want it. They'll always look for reasons why they should get it cheaper but it's just part of the game.

Do you look for a four bed house, must have hot water tank in not combi?

The OP is going to live life there for himself and his wife, not for people he doesn't even know.

 

[RobGra]

The boiler should suit the user not the house in my opinion but if you go the combi route think about proximity of DHW to outlets to source. Also think about the implications of reusing old gravity domestic pipework on a combi, it’ll be too large a bore leading to wastage and delay. If cylinder is new keep it, it will be well insulated, if not a combi might be something to consider. Too many unknowns for a forum, find an experience plumber to advise and take time to weigh up options.

Thanks all.
The cylinder is well insulated, and seems to be in good condition, ditto the pipework which is 15mm and 20mm to bath.
It's a difficult decision....

 

[ericmark]

Solar power often makes more electric for your needs, using the excess to heat DHW seems a good idea, also when I looked at oil combi boilers it's a cheat, just a system boiler with hot water tank inside the boiler.

My house boiler 19 kW oil, system boiler, sons house 35 watt gas combi, seems very big, it did have two 20 kW boilers one for DHW and one for CH, does not seem right to fit such a large boiler.

 

[RobGra]

The title for this is wrong, it should read "Combi v Regular Boiler.

 

[pcaouolte]

The title for this is wrong, it should read "Combi v Regular Boiler.

But the same comments apply. Keep your stored hot water.

 

[roguetrader]

If the layout suits, why not install a combi to do kitchen, utility, cloakroom or whatever you have and keep the cylinder as a separate zone to do bathrooms.
If you really like the combi, get the pipework swapped over at a later date.
Might not work on your property layout, but might provide a compromise.

 

[RobGra]

But the same comments apply. Keep your stored hot water.

Alas, there's a subtle but important difference, converting to a system boiler from regular, means a pressurised system, and fairly major work, ditto conversion to a combi, and question mark over existing pipework being pressured.

 

[pcaouolte]

Why do you want a pressurised system?

 

[RobGra]

Why do you want a pressurised system?

I don't necessarily want a pressurised system, however, I would like FW in the upstairs bathrooms, at same pressure at the HW, therefore combi or system boiler is the only way.
But if it's too much hassle & nausea, I'll stick with an open vent system. I'm just trying to get opinions before I pull the trigger.