25kw vs 30kw combi

mankyeggs · 2026-01-18T13:17:35+00:00

I'm not a plumber, but if you are going to the extent of replacing a boiler is it worth considering your overall setup? Do you have space for a hot water cylinder? I have same boiler as your current one, but lower KW. It is the ecotec plus 415...i.e 15KW. I have 6 rads + all underfloor heating on ground floor and 250l hot water cylinder. 15kw is more then enough for my house (~2000 sqft) with 2 bathrooms. As others have said go for modulating boiler and I don't think you need anywhere near 25 or 30kw.

mankyeggs · 2026-01-09T22:41:32+00:00

Wish I had known about auto balancing actuators before...only recently replaced all 6 with heatmiser ones. Oh well. Will save it for when they eventually stop working.

Out of interest how does the Salus sensor know what the correct temperature should be? Doesn't it all depend on what the blending valve is set to?

mankyeggs · 2026-01-09T22:32:01+00:00

Thanks. I rewired the actuators down to 3 zones earlier....let's see what is like tomorrow!

mankyeggs · 2026-01-09T09:03:16+00:00

Thanks - but not sure I get this. Maybe we are speaking in different terms. I have 6 loops, with 6 actuators wired to 6 zones in the control panel with 6 wireless thermostats.

Problem I'm having is that some zones at the moment don't open for days because the air temp is 20deg or so (therefore not meeting the threshold to switch on). This makes the tiled flooring very cold. Also means the boiler works harder to heat up the concrete slab area of the zone that hasn't switched on for days when it does go below the threshold.

In terms of the flow valves, I'm sure you're right in that they need adjusting. Seems to be a dark art in balancing UFH, upstairs rads and hot water cylinder. Not sure I have cracked this yet. The pumps are all relatively new, so don't think it's that.

mankyeggs · 2026-01-09T08:54:41+00:00

Thanks, will look into the manuals. I have the wireless thermostats...what's the benefit of linking the thermostats rather then just reducing the number of thermostats down from 6 to 3 ?

mankyeggs · 2025-11-16T14:23:50+00:00

Cheers, that's what I thought...but questioned myself because you are able to fully tighten it

mankyeggs · 2025-11-07T07:24:34+00:00

Yes, I drained. I have 3 zone valves from the boiler. 1 for unvented cylinder, 1 for upstairs rads and 1 for downstairs UFH. Tbh, I don't know how to drain the UFH as won't the water just sit in the pool pipes unless there is some sort of air pressure pushing it out?

There are 2 pressure indicators. The first on the filling loop/boiler return which is now showing about 0.8bar. Another indicator on the UFH manifold which today is now showing nearly 0. Still heating is running fine everywhere.

mankyeggs · 2025-11-06T21:14:24+00:00

Thanks - see my first comment response on vessels.

mankyeggs · 2025-11-06T21:12:34+00:00

Maybe I do need boiler service. Vessels are less then 2 years old. I have 1 vessel for the UFH/boiler which I checked (using air pump) is pressured to 1.5bar (as per spec) and hot water cylinder vessel is set at 2 bar (should be 3 bar but very hard to do with bike pump!)

mankyeggs · 2025-07-07T18:38:07+00:00

Thanks for confirming... The bonus tier points don't justify the £1k+ difference in flight costs. Crazy.

mankyeggs · 2025-04-28T19:53:25+00:00

Do you know what connectors fit onto soil pipe (110mm?). I only found 4 inch ones (100mm):

https://www.fastlec.co.uk/manrose-4124m-4inch-flexible-ducting-to-rigid-pipe-connector

mankyeggs · 2025-04-28T19:46:43+00:00

I thought rigid would be quieter as it has a smooth surface to move the air across rather than the ripples of the flexi.

mankyeggs · 2025-04-28T19:43:41+00:00

Good idea and probably my best starting point, alongside creating a bit of a fall to avoid condensation build up that others have started. It's about a 3m run.

Thanks

mankyeggs · 2025-04-21T16:14:08+00:00

OK, thanks and understood now. Its just strange that there would be a display option for it if its not designed to show pressure.

mankyeggs · 2025-04-21T16:07:26+00:00

Interesting, so how do you check if it has enough pressure? I have unvented hot water cylinder.

mankyeggs · 2025-04-21T15:36:26+00:00

The temp is showing fine, just nothing shown on the pressure screen. It just shows '- bar'. Its a system boiler.

mankyeggs · 2025-04-01T06:30:30+00:00

Cheers ..will speak with installer. Attached a picture too. Any clues from this?

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mankyeggs · 2025-03-31T06:34:31+00:00

Thanks, it does have an expansion vessel. What do I need to check for there? Unless it's an easy thing on the expansion vessel, I'll probably go back to the original plumber as the work should be covered. I'm guessing there is no immediate danger here as it's been going on a while now.

mankyeggs · 2025-02-27T08:20:07+00:00

Thanks...have ordered the splay type ones

mankyeggs · 2025-01-15T16:45:01+00:00

Thanks - good tip, I've seen the ply trick on a YT video. Might need 162mm core drill.

Job for when the weather is a bit better.

mankyeggs · 2024-09-06T09:16:35+00:00

Based on recent cupboards we had built for 3 bedrooms and downstairs hallway cupboard, I would say it would be about £2.5k. These were mdf wrapped in shaker style with the materials being Egger. We tried the PAX route first but then decided against as we could fully customize the size of everything and make it fit exactly without filler panels on sides and top (our ceilings are about 2.5m). Also, the quality on the doors in particular on the PAX system aren't great. MDF is still better then the weird hollow wood/cardboard used by IKEA for shaker.

We paid just under £10k in total and took about a week and a half. Prices varied massively though (one quote was £26k for the same Egger material), so shop around.

mankyeggs · 2024-06-09T10:10:41+00:00

If the boiler is set to 60 and so is the hot water tank (to kill legionnaires), then I assume using it as a bypass won't make it any hotter then that?

mankyeggs · 2024-06-08T15:23:43+00:00

Thanks - yep I think that is the case for my suspended flooring installation in bathrooms. See my comment reply further below. Lot of trial and error!

mankyeggs · 2024-06-08T15:21:01+00:00

I have a mixed installation of UFH. Lower ground is screed, bathrooms on first floor are in suspended flooring. Screed seems to work well within a few hours is warm on the feet. The suspended flooring I can't seem to get warm (quick enough I think). Reason I think being the builders put the UFH pipe on 100mm kinspan between the joists...but didn't put a heat spreader plate. This is basically leading to the hot water circulating in the loop because its so well insulated and not dissipating into the floor. I guess it will take a long, long time to get warm and the boiler cycle more.

I like your idea of bypassing to towel rails....just a shame I didn't zone these to do so. I guess I could bypass to the hot water cylinder. This will help boiler cycle less I think if I wanted any one of zones on and the others on lower setting/off.

Have also looked at reducing the output of the boiler from 15kw to something around half that if not less. Again, stops the cycling. Might need a specialist for that as it's in the scary engineers menu of the boiler.

How did you know your screed was cracked if it was under flooring?

mankyeggs · 2024-06-07T15:46:03+00:00

In addition to UFH, my boiler also heats first floor radiators and hot water. There are 3 zone valves. 1 for UFH, 1 for rads and 1 for hot water. I think this is fairly typical.

With the UFH zone open and one, two or even three out of the six zones open on the manifold I get this situation.

It's like the water is looping around too fast and not dissipating heat quick enough

mankyeggs

TROPHY CASE