Advice needed : System boiler to combi boiler changeover

philadvalorem

Hi folks,

Have an ancient system boiler and looking to change to combi system.

It's a 1970s gaff with 7 rads and a single bathroom (with no bath). Current boiler is in the kitchen.

There is a small amount of gun barrel visible in hotpress and on the flow into the hall rad.

Ground floor is concrete slab so cannot go near the gun barrel until I have money to redo floors and tiles in kitchen.

Everything else is copper and a small amount of pex where I did some alterations last year for cosmetic reasons.

No visible leaks or anything to indicate a pipework problem.

Wouldn't be doing the bathroom but even if doing so in future not particularly fussed about a high pressure rain fall shower..

Have had a number of quotes - but each engineer has a different opinion of what I need and/or how it should be done.

I see some heating engineers are quite active on this thread so hoping for an independent view on the following:

Question 1: Power flush or chemical flush?

Some are insisting I must power flush the system.

Others are saying it could be a risk and I will get more or less the same result with a chemical flush and a larger magnetic filter.

Is there a right answer?

Question 2: Is a pump required?

Some say these boilers are installed onto the mains in the UK etc without any issue, and I have the mains pressure so no pump needed.

Others says that may be so, but mains pressure may not be like that forever, and you need to consider demand at peak times etc

Is there a right answer?

Question 3: if I need a pumped system, does the whole install need to go in the attic?

Some say the boiler can go in the kitchen - handy spot - and the pump in the attic.

Others say I need to run the gas line up the outside into the attic and locate boiler and pump there.

Is there a right answer?

Thanking you all in advance,

Confused new homeowner

Edit: Probably obvious but should have made clearer the different opinions are leading to widely different costs.

I'd like it done right, but budget is an issue and some solutions appear over-engineered (admittedly to my non-expert eye)

Also, important to say there is no room for a second bathroom - so it'll only ever be hot water supply to kitchen sink and the shower and sink in the jacks

Sleeper12

The correct way to install a combi in Ireland is to take the feed from the cold water tank in the attic. You then pump it to the combi and also pump the cold supply. This way you will have equal pressure. Thermostatic showers require equal pressure to function correctly.

Personally I'd stay away from anyone trying to talk you into connecting into the mains water supply. They haven't taken the trouble to read the building regulations on how to connect a combi boiler in Ireland

philadvalorem

https://www.boards.ie/discussion/comment/122603846#Comment_122603846

The majority of heating engineers who've called out have recommended connecting to the mains, but from what I could find online it seemed wrong.

However, it was hard for me to be sure because most online info refers to the UK. They seem to have a different approach to here, and that just added to the confusion.

Thanks for the response, if the regs says there's one way, then I'll go with that.

Would you have any advice re: power flush / chemical flush?

Also, in terms of pumps I've been quoted for a submersible by one guy but another says there's no need, a separate pump sitting on a noise dampening mat will work

Again there's a fair price difference. Would appreciate an independent opinion on pros/cons of either option.

Thanks again

Calahonda52

Sleeper is right here and even if the regs didn't say it I just would not do it.

Chemical vs power flush, my concern is that you run the risk of leaks in rads, but more problematically in the GB in the floor if thy are 1970.

Can you locate the pump outside of the house as it may be noisy internally, eg if someone runs the WHB at 3am after a bad curry

Maybe use the opportunity to relocate the CWT to garage and out of attic. these have pump and all, plug and play

You really dont need a gas line on the outside of the house, what if u wanted to do EWI?

philadvalorem

https://www.boards.ie/discussion/comment/122604331#Comment_122604331

Unfortunately no garage so the pump would need to be in the house somewhere. Noise is a concern, would the tank you recommended be quiet?

Not sure why, (maybe easier for them) but both guys who were recommending boiler and pump in attic wanted to run pipe from the gas main outside straight up the wall and into attic.

EWI - I'm guessing external wall insulation? Don't think I'll ever have money for that especially with the quotes I'm getting on the boiler 😂

My alternative is just to replace current boiler with another system boiler.

I was looking at a combi mainly as hot-press is in bathroom and I'd get that space back, but it seems to be coming in at such a cost it's getting hard to justify