System Boiler vs. Combi Boiler vs. Heat Pump

VonLuck

I am currently due a service on my 20 year old system gas boiler but I am considering a complete replacement due to its age. I believe the boiler would originally have had an 80% efficiency which I can only imagine is greatly reduced now after the length of time its been around. There also appears to be water leaking from it which is only a recent development.

I have had an ongoing problem where the pressure would drop continually and I would need to top it up ever couple of weeks. There have been zero visible leaks (besides the most recent one) and some people suggested it could be a leak in the coil in my hot water tank, but I've no way of knowing for sure. I had a separate expansion vessel installed last year (at gas boiler company's suggestion) but it doesn't seem to have worked at all.

So instead of getting my annual service this year, I was going to upgrade my boiler. I am in an apartment and the boiler is located on the balcony and the tank in a hot press about 8m away. I'm weighing up the options which seem to be the following:

1. Install a new system boiler with higher efficiency. No guarantee that this will resolve the pressure issues.
2. Install a new system boiler with higher efficiency AND replace my water tank. Should hopefully resolve all my pressure issues.
3. Install a new combi-boiler. I am hoping this will fully resolve the pressure issue if the hot water tank is no longer required. Will require additional flow and return pipework to my hot press. Hot water tank would be defunct, but will need to keep cold water header tank (which is part of the hot water tank) to supply the combi.
4. Install a air-to-water heat pump. May be a costly installation but would likely provide cheaper bills and more comfortable apartment temperature.
5. Service my existing boiler until it no longer works. Gas bills will continue to be higher than they should be and I would need to keep topping up the pressure.

To me option 3 seems like the best option, but then there is a concern about gas becoming obsolete and not future proof. I am no expert in this area so I would appreciate some advice!

Yellow_Fern

If you get a system gas boiler, make sure you get a good one with modulation, weather compensation and opentherm or something similar as a lot of gas boilers lack this and this perform much weaker than marketed as.

Heat pumps are great but make sure you have a proper heat loss calculuation before you commit as you might not actually save money with them if installed badly.

declan b

new gas boiler and find the leak is your best option

VonLuck

Is a combi boiler not worth it? I thought it might be cheaper and more convenient in the long run.

Yellow_Fern

https://www.boards.ie/discussion/comment/123028859#Comment_123028859

Would be interested to hear what others say. I guess combi is great for smaller households. Might be worth checking out if Heat geek on Youtube as any feedback on them.

The lips

I am interested in how this thread goes, I am also going to change out my system gas boiler, I fancy a combi if the retrofit is not too extensive.

My water softener will have to be routed through the Combi too. Any suggestions on most reliable water softeners?

xl500

Don't forget combi needs a break tank against regs to connect directly to mains and before I get savaged for this please see Irish Water regs

The lips

Yes I had two guys in, one wanted to connect to mains, the other was correctly pumping from the attic tank.

VonLuck

https://www.boards.ie/discussion/comment/123043791#Comment_123043791

I was intending on just keeping my old system boiler tank and empty the hot water part of it at the bottom as it would be redundant.

Someone gave me a run-down of what would be required to upgrade my system boiler to a combi and it seems to be extensive (i.e. expensive!):

• Install new combi boiler in the same location.
• Remove existing pump and install walrus booster pump.
• There is a void in the ceiling in the hall way, make a hole in the hotpress and try fish hot and cold back to boiler on the balcony at underside of bedroom room ceiling.
• Extended flue with Co alarm.
• Condensate to terminate on balcony with neutraliser.

Does this sound normal? Why do I need a booster pump and an "extended flue with CO alarm"?

I was also hoping I could fish the hot and cold pipes to and from the boiler myself using Pipes and avoid the extra cost of someone else doing it. They would just need to connect up at either end. Does that make sense?

standardg60

https://www.boards.ie/discussion/comment/123050665#Comment_123050665

Yep sounds right, retro fitting a combi is messy (expensive). The pump is to provide circa mains pressure to it as that's what they use (hence why some are connected directly).

And no i doubt any installer is going to accept you doing some of the work because they can't stand over it if something goes wrong.

VonLuck

https://www.boards.ie/discussion/comment/123052522#Comment_123052522

I already have a pump that sends hot and cold water to my taps from my tank. Does that mean I need two pumps - one to the combi boiler and then one back to the taps?

Regarding the installer having issues with someone else doing some of the work, is this not always the case when they replace an existing one? They're not going to say that they can't stand over all the existing pipework going to my hot water tank / taps because they didn't install them.

VonLuck

https://www.boards.ie/discussion/comment/123052995#Comment_123052995

Any thoughts on this? The quote I got previously was about 8k and was hoping that I could cut it down greatly by doing some of the work myself.