Replacement for Danesmoor Utility 32/50?

[Max]

My Danesmoor is on last legs. Actually was when I posted on here two years ago asking about Firebird as a replacement, but limped along. Now however the writing really is on the wall so need to replace this summer.

Heating engineer is wedded to Firebird but not heard good things about out of warranty customer service or reliability and I don't like their constant parts replacement policy. When I posted on here couple of years back, SimonG highly recommended Hounsfield, and given that heating system is now fully zoned I did think I might get away with it, because sadly biggest boiler Hounsfield makes is a 26/30. Current Danesmoor jetted at 42 (output). But now having done calcs for the whole house I can see that on a freezing day with high demand the Hounsfield most likely will just not cut it. Pretty gutted because had contact with Hounsfield and very impressed in every way, but calcs are calcs sadly.

So the question, ruling out Firebird, and some on here seem to think Grants are leak-prone, wonder what people think of the new WB Danesmoor Utility? Is it pretty much the same boiler as the old one, or is it the same in name only? Had a WB gas floor standing combi in old house about ten years ago and was good but when needed parts blooming expensive. So the current Danesmoor Utility 32/50? Good or bad? If bad, then what recommendations?

Thanks for looking.

 

[SJB060685]

Firebird in my opinion are pretty decent. I know a number of engineers who swear by them and have no problem with warranty if needed. You could consider the Navien?
If you rely like the idea of a Hounsfield why not consider cascading two with a low loss header and decent sequence controller.?

 

[ShaunCorbs]

What’s your Heatloss calcs coming out at ?

 

[exedon2]

As a business we change 2/3 oil boilers a week most are fairly elderly but in last year we have changed several wb boilers way less than 10 years old one less than 6 also warmflow and firebird boilers less than 10 years old.
During the last 5 years we have taken just one leaking grant that was 11 years old and had been appalling installed.
I would agree grant combi's had a reputation for leaking on the appalling auto air valves but there no longer fitted.
Having fitted several hundred grant boilers virtually all of the small amount of warranty work is burner related and majority of that was when riello had photocell problems.

 

[Max]

Heat loss calcs were done several years ago when we looked at possibility of GSHP (which was therefore discounted by the way). Came out 34kW but that did not count a small annexe we also keep at a background low heat to keep damp at bay.

Then as a cross check I yesterday went around the house and sized up the rads for heat output (kW). Total max possible output came to 38kW. Not had much in the way of long freezing spells recently, but I also recently installed fully zoned system and we would rarely want full heat in every room simultaneously + loft is very poorly insulated which I am about to address. I know in the coldest snap last winter that the current boiler did manage to keep the house warm enough.

Now wondering of the Hounsfield at 30kW might just do it at a push after I've really gone to town on loft insulation.

What’s your Heatloss calcs coming out at ?

 

[SimonG]

Hounsfield.

 

[SJB060685]

The system should typically be designed at an outdoor temperature of -2 -3 °c and a room temperature of 21°c. If you undersized the boiler you can expect poor performance in extreme weather.
I say again, if you have space why not cascade two boilers and a LLH and a decent control system?

 

[Max]

The system should typically be designed at an outdoor temperature of -2 -3 °c and a room temperature of 21°c. If you undersized the boiler you can expect poor performance in extreme weather.
I say again, if you have space why not cascade two boilers and a LLH and a decent control system?

I guess it seems overkill to pay for and install two boilers when it's so marginal and more powerful boilers are available. I guess my situation is a little unusual in that the heating demand could vary quite widely. I can see a situation where I install two Hounsfields and one sits almost totally unused for the vast majority of the time. In fact that's exactly the situation Andrew Hounsfield told me about for one of his installations. Large B&B, two of his 30kW boilers installed, but owners say the second boiler has hardly ever fired because for 95% of the time the first one is nearly always adequate.

So here is another question. What's the worst sin in system design? Overpowered boiler running "light" or underpowered boiler running flat out?

So for example, whole of my downstairs system demand calcs out (by rad sizing) at around 23 kW, but even that is zoned - for example, largest room in house (kitchen, underfloor heating) has own zone, so does hallway, also lounge which also has wood burner available) , utility room and then remaining rads as the last zone) and upstairs is total of around 10 kW which on cold winter nights I might leave on all night at a background level. Then the bathroom towel rails/rads are all on the "hot" side of the boiler at around 6kW. So at night, you could have situation with (as at present) 42kW boiler only heating 16kW (upstairs and bathrooms).

Simon, interested you still say Hounsfield. Any further experiences since your last recommendation 2 years ago?

By the way, in the heat loss calcs, the person who did them spec'd it all with outside temperature -5C, downstairs living rooms at 21C, bedrooms at 18C.

 

[SJB060685]

Theres no problem downsizing a boiler to a lower KW output if it can match total load but undersized boilers will never be enough to bring the dwelling totally upto to temperature on extreme days.
You can argue that two boilers in situ, one will always be fired and the other not so much but that is not true. A decent sequence controller can stagger the boiler inputs so they are equal throughout the year.
Another option is a buffer tank sized appropriately for your needs. Then the output of the boiler only affects the reheat time of the store.

 

[Max]

Theres no problem downsizing a boiler to a lower KW output if it can match total load but undersized boilers will never be enough to bring the dwelling totally upto to temperature on extreme days.
You can argue that two boilers in situ, one will always be fired and the other not so much but that is not true. A decent sequence controller can stagger the boiler inputs so they are equal throughout the year.
Another option is a buffer tank sized appropriately for your needs. Then the output of the boiler only affects the reheat time of the store.

Should also have mentioned tight on space for two boilers unless I move the location (not impossible but a hassle) but thanks for info because certainly not ruling it out. With price of oil I get through in a year cost of an additional boiler not that massive taken over many years even if it saves 10-20% a year in oil cost.

Sorry folks, last question (I hope). Hounsfield just threw in a curved ball by announcing they just now introduced a different burner for their boilers (just seen email come in today). They did swear by reliability and serviceability of the Bentone BF1 but they seem to have replaced it with an Elco burner:

Any comments?

 

[SJB060685]

Should also have mentioned tight on space for two boilers unless I move the location (not impossible but a hassle) but thanks for info because certainly not ruling it out. With price of oil I get through in a year cost of an additional boiler not that massive taken over many years even if it saves 10-20% a year in oil cost.

Sorry folks, last question (I hope). Hounsfield just threw in a curved ball by announcing they just now introduced a different burner for their boilers (just seen email come in today). They did swear by reliability and serviceability of the Bentone BF1 but they seem to have replaced it with an Elco burner:

Any comments?

I can assure you the Elco burner is tried and tested and performing very well. It's also been tested on HVO (Hydrotreated Vegetable Oil) which I suggest you have a read up on!

 

[SimonG]

They've used the Elco burner for quite a while now. Nice reliable burner.

 

[Max]

They've used the Elco burner for quite a while now. Nice reliable burner.

OK, thanks for the responses. So now in light of the Elco burner being a decent unit I am leaning back towards Hounsfield again, try it for one winter. Hopefully I am right and with zoning and much upgraded loft insulation it will prove OK and if it proves a bit under for my purposes, move boiler to new location and install additional smaller boiler for "top up" when needed.

Thanks for responses. Helpful.

 

[SJB060685]

OK, thanks for the responses. So now in light of the Elco burner being a decent unit I am leaning back towards Hounsfield again, try it for one winter. Hopefully I am right and with zoning and much upgraded loft insulation it will prove OK and if it proves a bit under for my purposes, move boiler to new location and install additional smaller boiler for "top up" when needed.

Thanks for responses. Helpful.

As you know increasing the thermal insulation of the dwelling with have a profound affect on load required. Loft insulation, double/triple glazing, cavity wall insulation etc etc etc are well worth the investment and will massively decrease the size of boiler you required.

Can I just ask. You say you have a large UFH circuit/circuits, have you ever noticed under performance in radiators on cold days?

 

[Max]

As you know increasing the thermal insulation of the dwelling with have a profound affect on load required. Loft insulation, double/triple glazing, cavity wall insulation etc etc etc are well worth the investment and will massively decrease the size of boiler you required.

Can I just ask. You say you have a large UFH circuit/circuits, have you ever noticed under performance in radiators on cold days?

No, never been an issue as far as I remember. Since we installed the UFH of course we had to introduce zones for that and also had water reconfigured from vented to unvented so while plumber was here got him to split upstairs and downstairs then I did a bit more myself (made use of some paralleled motorised valves left over in some odd locations (lucky). People that lived here before, guy must have had circulation problems as some rooms were hugely over specced with rads, so I actually removed probably half a dozen rads, but boiler has not changed. Loft insulation appalling (about to rectify) and already has cavity insulation (where we have been able to see it anyway), and of course anything we added we insulated. All windows double glazed.

Yep, I was taught about value of insulation when building last project. Pretty much ground up so was fully insulated to latest specs. Boy, did that teach me a lesson. Having lived in old drafty houses all my life before never realised before that what a huge difference insulation can make as you say. Huge. But now back in an old (and much modified) house again so trying to make the best of it as I go.

Interested to know why you ask about the rads on cold days? Although yes, UFH is quite a large area, it runs quite a bit lower in temperature via blending manifold of course. Works well but I would do differently again if I had another chance. Laid UFH at 200mm centres. Now (for any older property anyway) for the sake of a bit more pipe I would go 150mm centres. In fact just looked at Underfloor Heating Store where I got my stuff and notice they don't seem to offer the 200m centre backer boards any more. Enough said.

 

[SJB060685]

The reason I ask is its quite common for radiators to under perform on cold days with the UFH heating working. You sound quite aware so I hope you understand what I'm saying.
If your UFH is on as well as the radiators the UFH will pull almost three times the flow rate of the radiators, which can starve the radiators of flow the lower the flow temperature is and the colder the UFH slab is. This can cause an under flow in the radiators, where they don't receive the required flow rate to keep up with emissions, in the worst case scenario they can actually cause reverse circulation through the radiators as the UFH tries to keep up. Only when the flow temperature is equal to the return temperature of the UFH plus 20°c will the system be in perfect balance, as long as the flow temperature is less from the boiler than that the UFH is likely to pull more and potentially cause issues.
Now, one thing that might be in your favour is up until very recently all domestic oil burners have been fixed rate (they fire at a certain output regardless of system demand) and any pump coupled with the boiler is not burner linked, unlike their gas cousins, so it is entirely possible that the system was designed and a suitable pump installed to cope and the system works fine as the boiler has no way of knowing the DT between flow and return and therefore no influence over boiler firing rate.
It's something you should consider because it's not uncommon.

 

[Max]

The reason I ask is its quite common for radiators to under perform on cold days with the UFH heating working. You sound quite aware so I hope you understand what I'm saying.
If your UFH is on as well as the radiators the UFH will pull almost three times the flow rate of the radiators, which can starve the radiators of flow the lower the flow temperature is and the colder the UFH slab is. This can cause an under flow in the radiators, where they don't receive the required flow rate to keep up with emissions, in the worst case scenario they can actually cause reverse circulation through the radiators as the UFH tries to keep up. Only when the flow temperature is equal to the return temperature of the UFH plus 20°c will the system be in perfect balance, as long as the flow temperature is less from the boiler than that the UFH is likely to pull more and potentially cause issues.
Now, one thing that might be in your favour is up until very recently all domestic oil burners have been fixed rate (they fire at a certain output regardless of system demand) and any pump coupled with the boiler is not burner linked, unlike their gas cousins, so it is entirely possible that the system was designed and a suitable pump installed to cope and the system works fine as the boiler has no way of knowing the DT between flow and return and therefore no influence over boiler firing rate.
It's something you should consider because it's not uncommon.

Strewth, lots to think about there, but no issues so far. UFH has own pump on manifold. I assume they all do? Or perhaps not? Actually in my system, the main non-UFH part anyway (inherited from previous owner remember, then hacked during renovations) the boiler is quite remote from the house. It's in an outbuilding that was previously used as an office, with pipes that run under tarmac nearly 20 meters before they enter the main house. Pipes I think from memory are 28mm insulated with some sort of thick corrugated foam covering. Must be pretty good because pipes are not a huge way below the surface and never seen ice melt above the pipes on the tarmac on a frosty day. Then just after it enters house there is another pump, both Grundfos old style three speed (fixed) non-modulating pumps, then of course the third pump on the UFH which Underfloor Heating Store techs (who supplied all the kit) told me to set on highest speed. I don't understand the theory behind having multiple pumps or if, after fitting the new boiler, the extra pump at the house end of the line should be retained or even necessary, or if removing it would put too much strain on the boiler end pump? Anyway, guess what I am getting at is that supply of flow, all pumped, is unlikely to be an issue I would have thought, unless I am misunderstanding something? I thought maybe you were referring to a system where the main pump has to power both the UFH and the rads, and the UFH manifold is just series of solenoid valves with no pump?

Anyway, certainly no issue at the mo with all four circuits of UFH flat out and all rads still piping hot. Blimey, now you make me wonder if I should be careful with erring on the low power side with the Hounsfield.

Apologies, we are wandering way off topic here, or maybe not as I guess it's all relevant to the choice of power of the boiler?

 

[ShaunCorbs]

If it’s working I would say leave as is also 30kw should be enough

 

[SJB060685]

Once you know your final heat loss and KW required you can size the boiler. Sticking in a 30KW boiler when your loads require 40KW (for example) is never going to achieve desired results.
I imagine the second pump, just inside the house is sized to supply full flow requirements to each zone and the boiler pump just gets water there. Not how I would like it done, pumps, can in series cause problems, although from how I'm picturing your layout I don't think that's the case here. If it works it works but I'd prefer a different approach as it's not ideal, however the alternatives would require major upheaval.
Yes the UFH manifold has its own pump, set on max setting.

 

[Max]

Once you know your final heat loss and KW required you can size the boiler. Sticking in a 30KW boiler when your loads require 40KW (for example) is never going to achieve desired results.
I imagine the second pump, just inside the house is sized to supply full flow requirements to each zone and the boiler pump just gets water there. Not how I would like it done, pumps, can in series cause problems, although from how I'm picturing your layout I don't think that's the case here. If it works it works but I'd prefer a different approach as it's not ideal, however the alternatives would require major upheaval.
Yes the UFH manifold has its own pump, set on max setting.

OK that's good information. Many thanks.